I have a toyota tundra with a plastic drop in bed liner. I also have a tonneau cover and a cargo bed rail system. The top of the bed liner is underneath the rails which are bolted on. I dont think I can just remove the bed liner and reinstall without messing with the rail system.

I want to remove the bed liner so I can clean behind it. I was thinking of cutting the bed liner just below the bed rail system and using that high strength 3M velco to reattach at several contact points. This way I could remove when needed.

Is this a good idea?

Why do you need to clean behind it? In 20 years of driving trucks with drop in bedliners I have never even considered cleaning behind or beneath it.

Unless you have a topper, I'm picturing the bed liner flying out of the back and onto the interstate. (I've had one fly over the car I was driving before, very exciting).

I would consider cutting it out completely and then having a spray in bed liner installed, I had mine done in 2003 and its still in the bed, no chips or cuts, held up to several moves, plants, rocks, etc.

That way you'll never have to remove the bed liner and you get good protection for the bed.

If it's an over-rail, you'll probably want to secure it some how; an under rail, not necessary, as long as it's a tight fit. I have an under-rail in my Tacoma that is not screwed in (save the tail gate part) and it is solid. You need to warp it wildly out of shape to get it out.

I'd cut it. Maybe you might be able to tuck part of it under your bed rail. After I cleaned under it I would consider spraying a light coat of WD40 on the metal before reinstalling. I had a bed rot out on an F250 from dirt and moisture under the liner.

I wouldn't worry about cleaning behind the bedliner.

I have a bedrug in mine love it would never do a plastic liner or that spray in stuff.

And the bed liner is for what? Do you consistently haul a lot of stone or bricks?

My 15 y/o truck has a bed that is pretty scratched up through the years old landacping material hauling and moves and is generally rust free. But, then again, its pampered and garage kept most of the time.

I've never seen a reason to not use a spray in liner. It's even better if you get the factory option.