With my 3/4 ton GMC Sierra Denali HD came a B+W gooseneck hitch. This hitch platform has a receiver for the gooseneck ball, which is removable. B+W sells a 5th wheel hitch platform that plugs into the gooseneck ball. The ball locking bar would attach the companion 5th wheel hitch such that the platform is loaded against the pickup truck bed.

https://www.etrailer.com/Goose...and-W/BWRVK3500.html

Having just pulled a rental 6500 pound trailer on the GMC bumper hitch, I’d like to try a rental 5th wheel trailer next. Several smaller 5th wheels would be within the 13K capacity of this 3/4 ton truck.

I would likely be selling a hobby item to fund the companion hitch purchase.

The comparison of 5th wheel to bumper pull rental trailers will point us to a future purchase.

Can you all think of any reason not to purchase the companion 5th wheel hitch? I would certainly try to find one used, given the new price at $1K. What risks would I be taking on? What benefits would I gain?

I'm confused by your post. For all practical purposes 5th wheel towing and gooseneck towing are identical. And just about anything you can buy can be had in either format.
I have the setup you are discussing (gooseneck in the truck, 5th wheel using it as an adapter, on a ford, but whatever). Its fine, all this stuff from major mfg. is well designed and proven.
I can't think of any possible reason for a future purchase to just not get what you want in a gooseneck and be happy and save the conversion.
My truck goes to 12.5K bumper pull and up till that size it really is the best option price wise. I only have the 5th wheel setup as I bought a specific trailer for a steal and thats what it was. The conversion kit was trivial in the total deal. I have a dozen trailers with gooseneck as that's my norm.
In any case no upside unless you have a specific trailer that needs it, downside is cost. But your not really risking much as these go used for 70-80% of new.
But not a chance if I was buying a new trailer I would bother to make it need the 5th wheel over the gooseneck.

I wouldn't think twice about finding a good used B&W Companion 5th wheel hitch. These can be had for good prices on Facebook market place. These are solid American Made Plates and give you great options on hitch types

As an example, I had a B&W Patriot that used ISR (Industry standard rails and priced it at $350 and still couldn't move it. It went with the truck when I sold it.

I have a companion 25k that is a gem sitting in my storage. Waiting for me to list it. I would recommend B&W.

What size is the bed on the truck, 6.5'? you might be okay with the gooseneck sleeve as long as the center point of the fifth wheel pin is at or behind the axle.

This is true as long as the fifth wheel is 96" wide. If you get a fifth wheel that is 108" wide, there is a good chance the trailer will hit the back of the cab on really sharp turns.

Ask me how I know....

BTW: We have the B&W Companion slider hitch and use the GM puck set up. It's a great hitch.

That’s the right hitch if you have a long bed. Get the slider version if you have a short bed. I’ve had the non-slider B&W for the Ford puck setup for 5 years and have no complaints.

Thank you for insights.

Renting a 5th wheel, I cannot convert it to a gooseneck format.

6.5 foot bed, four door pickup…sounds like a slider is required.

My understanding is the slider is used when backing into campsites or other times you may need to backup and turn. It gives more clearance between the 5th wheel’s overhang and the cab of the truck. If you only use pull-through campsites maybe you don’t need the slider? Some 5th wheels are designed either with less overhang or cutouts on each side of the front cap to give extra clearance when backing into tight spots.

The one thing you have to watch out for with a 5th wheel is kingpin weight. That’s where 3/4 ton and SRW 1 tons run into problems. The kingpin is the pin on the 5th wheel that connects to the hitch. About 20-25% of the total weight of the 5th wheel is there and thus carried by the truck. The payload of your specific truck is probably shown on the same sticker that shows what the tire pressures should be found on the door jamb of the driver’s side front door. Subtract from that number the weight of anything you’ve put in or on the truck since new.

For example:
Say the payload number is 2,500 pounds. You’d subtract the weight of the aftermarket B&W gooseneck hitch and the 5th wheel hitch you plan to buy. The gooseneck is about 100lbs and the slider is about 200lbs. Now you have 2,200lbs of payload. Subtract the weight of the tools under the rear seat, fuel, passengers including the dog, and anything else you plan to carry in the cab or bed of the truck. When you hit zero and start going negative, stop because you need more truck.

Taking a hypothetical 13,000 pound 5th wheel with 20% of that on the kingpin, you are already probably over the payload of a 3/4 ton truck. That kingpin is about 2,600lbs by itself and the hitch and subframe add another 300lbs for a total of 2,900lbs.

You can verify this by getting two weights of you truck and trailer at a CAT scale. The CAT scale weighs front, rear, and trailer axles at the same time. Get the first weight with the trailer hooked up and the second with the trailer unhooked. You just disconnect the trailer while you are on the scale. The difference in the trailer weights is the kingpin weight. Also pay attention to the rear axle weight. There’s a good chance you’ll be over the load bearing capacity of the rear tires if they are inflated to 65psi.

I had a B&W Companion Turn Over Ball slider, which weighed in at just over 300 pounds, and used it in two F250's, both of which had the 6' bed. I found that I didn't need the slider function with our new fifth wheel due to the front cap having angled corners. With my new 20220F250 I had the pucks put in and bought the non-slider B&W Companion. The new hitch weighs in at 80 pounds, so there is a significate weight difference between the two.

I have the non slider that I use in a 6.5 foot bed F250 and have never had an issue.

Many of the newer 5th wheel trailers have rounded noses to help with the issues of a shorter bed.