If I end up building another -7A, here are some things I'd do next time to make installs a little easier cleaner and faster. I'm not telling you to do this, just saying what I'd do as I have a better idea how things are placed now. Certain things I like and would stick with, certain things I'd change like performing several of the firewall penetrations prior to installing the motor mount and engine.
Might as well go ahead and install a flush rivet just above the rear spar attach point as the raised rivet interferes with wing sweep for many builders. If you're going with lights/electric trim in the tail, I'd go ahead and pull and anchor the electrical wires in the back side while it's still open and you can drill nice clean holes etc. Going with standard master solenoid and starter solenoid as in the Vans plans, you could put those in while they are easy to get to. Same for battery box. Just stay with the location dimensions as called out in the plans for the particular engine you plan to use. I would not punch the holes for throttle/mixture/prop controls though. I think my locations are better than what the plans call out. If you're going with the heater valve (I went stainless steel with cabin side control), you could punch that hole per the plans and save yourself some trouble crawling around the cabin floor as I did when I installed mine. Next time, I'll install my antenna mounts and reinforcements while I can turn the canoe over and access things. I'd add one or two more conduit holes from the baggage area bulkhead thru the rear spar before installing floors BUT I'd call Vans before I did to make sure I'm not adversely affecting the airframe with that modification. My ADHRS is back there along with xpndr, ads-b, elt and wiring plus pitot/AoA tubing is crowded. I'd also drill my aileron trim servo to the seat rib before installing the seat floors just to have better access. I used the click-bond type standoffs/anchors for tying my wiring down. I'd install a lot of these in areas where there would be no direct riveting while they are easy to get to for cleaning and prepping areas befor installation. Install static ports and tubing while top skins are off. Basically, just do everything that you possibly can do before you have to close things up for good.
I have not run into any impossible areas but I have had to turn into a bit of a head scratching, groaning, contortionist, that adds a mild expletive at times in order to get the job done. Next time would be easier to see ahead and know what you can reasonably do ahead of time to make the build somewhat easier. Nonetheless, It's definitely a labor of love.
