I have to agree that removing the pop-top is not necessary.  I removed mine though to kill the mold in the roof "fuzz".  I could not get anything to work, but when I used bleach AND let the top sit in the sun, the severe mold problem I had was gone with no scrubbing. Note that it is tricky to put back on the van without scratching the roof paint - especially when you can't convince your help to be careful on the paint when you have an ugly dented van!

Now, anyone is going to replace their canvas - read-on!

A little trick I used when putting the canvas on addressed the problem of checking the fit (roof fully up) and attaching the canvas (some slack in the roof - i.e. lowered a bit.)

I tied a rope from the horizontal "pull bar:" (The bar you push or pull on to pop or un-pop the top) to the other horizontal pop-top bar  This limited it's movement so that the top would retract a little, but not enough to squish me as I was lying in the top bunk.  Let's call this the "limiter rope".  I also tied a separate rope to the pull-bar and led it back to bed. Let's cal it the "pull-rope".

So, AS I was lying around up there, I could just pull the pull-rope and the top would retract a bit, its movement controlled by the limiter rope.  Then to pop the top back up to check the fit, I would push the pull-bar with my feet, which was only a foot or so of movement and pop the top all the way back-up.

I also used PLF canvas (3-window) and am happy with the product - although mine lacked the rear elastic. Maybe they have then now. However, my wife said that after a while the canvas will get a memory and fold correctly.  But until then you need someone to tuck it in a bit in the back.

The next thing to being clever is being
able to quote someone who is
-Mary Pettibone Poole