I think there's a writeup in the link in my signature. and yeah, it is that easy. hardest part is usually getting the old stuff out if it's rusted or original.
technically it said 20gal, but that's definitely not right and thus far all sheets that said 20 (that I've been able to confirm with owners) have been 23s, so I change it to that.
but what exactly is the purpose of that? it just feels to me like you're ruining the bed so you can protect the bed. I guess if the bed is already pretty rusty it'll hide all that, but it'll also trap dirt/moisture/salt between the new and old steel and likely accelerate the rust.
ahhhh... from a percentage-of-total-miles-driven-each-year it seems to me like a 30 year exemption would make more sense. how many late 70s rigs can there possibly be still on the roads?
life seems to always be... complicated. I find a bit of solace in the consistency of my Jeeps. (consistently needing work, but consistency none the less. lol)
biggest tips I've read about installation is let it warm up in the sun first, then start in the middle and work out. also, don't cut any of the edges until you happy with everything.