I bought a 1972 XR7 convertible a couple of weeks ago, so I’m trying to learn any tips and tricks that go with getting the boot to cover the convertible top. I’m pretty sure the top was replaced at sometime during the car’s 48 year history, and the canvas material may not let the top compact into the well as much as it may have with vinyl material. Are there tips on securing the boot other than the 3 snaps on each rear interior panel and the slot that goes across the top of the back seat? I would like to avoid adding snaps to the molding.
As the former owner of a '73 XR-7 convertible, I can offer the following advice.
If you have the correct style boot, the best way to install it is as follows: first, make sure the latches are back in their “latched” position after the top has been fully lowered, so the J-hooks don’t stress the boot vinyl/fabric. Next: press the “front” of it (the portion that goes along the top of the rear set top) into the lip along the top of the seat. Then, slip the small plastic tabs along the rear edge of the boot under the chrome trim. I used to start in the middle, go one direction, then the other. Lastly, snap the snaps to the interior quarter trim panels last.
It also helps if the boot is a bit warm, as the vinyl will stretch more easily.
I have a 71 vert with the canvas top, (see WCCC video on top replacement) and your right the canvas top does not sit as deep in the well as the original top did. I also have the original boot and a new reproduction boot. I have also put a thicker pad under the new boot than it came with. I have tried all kinds of different ways to put the boot on. I also found that the top will billow up out of the well 2-3 inches without the boot in place while driving. I have found that putting the boot in the sun about a half hour before install helps immensely. I then fasten three snaps on one side, place the front of the boot into the grove on the back seat and then fasten the other snaps on the other side. I then start in the middle rear and work around one side and then finish from the middle around the other side. By pulling the boot forward I can work out the bulges where it goes under the chrome. It also helps the top to sit deeper if you unzip the window and tuck it in by hand. I still use the original boot if I use my parade pad (a board with thick padding for someone to sit on) so I don’t stretch the new one. It is snug and a hassle at times I know but the finished look is worth it. I would not in any way put snaps on the chrome channel or boot. I doubt you would ever get them sealed as the screws would go all the way thru. We have several verts here in the yard that have lots of corrosion and rust from the screws in the snap.Hope this helps! As much as I love the look of the tan canvas with the maroon paint, if I did it again I would go back to the white vinyl.
X2 on what Richard said about not doing the snaps…I’m pretty positive my top and boot are not original. My boot always pulls up in the rear passenger side corner no matter what, and being in south florida sitting in the sun doesn’t help lol. So I only put it on for the occasional cruise in, I don’t do any 70 mph interstate driving so not doing the boot hasn’t been an issue driving wise. Also being in FL all day car shows I put the top up so the interior doesn’t get baked, I drive in and out with the top down cause its such a nice cruise. I know that doesn’t help with your question, just my experience 
Thanks so much for the advice!! Richard, really appreciate your videos-I upgraded the lights to LED based on your “How to” presentation.
My '73 has the original top. I’m now using a replacement boot because the original was sacrificed for seat repairs. The tip above about putting the latches in the locked (lowered) position is great advice. But I’m here to tell you that, with original or replacement, hot sun or clouds, the rear corners are going to lift out of the track at speed. As long as the front and snaps are secure the boot will not fly off even at 100 MPH.