Congrats on the Tiger!!
I'll echo what Diplostrat said about the chill at the top of the older Tigers - that fiberglass top does nothing to keep you warm, and you live where the winter is real. Even if you lose a little storage space, I'd tack in some insulation up there in the cabinets. Also, where you're removing the shower pan - that and the bottom of the closet are the weak spots in the plumbing for temperature exposure, at a minimum wrap the pipes in foam insulation. The low water drain *might* be at the stopcock in the closet but 2 of my previous tigers it was actually under the shower pan, so don't count on it. Always blow the line clean with air when you're in freezing temps. I doubt you have heated tanks, those came later. Even heated tanks don't help with that small diameter plastic plumbing.
I'm totally impressed with your gutting the interior :Wow1: Mine could definitely use some sprucing up back there. Now look what you've started! Are you pulling all the cabinets in the kitchen too?
I was at Tiger central in SC a couple years ago and had them pull the carpet and replace the subfloor and new vinyl/wood-look flooring. So nice to be able to sweep it clean now. Underneath that carpet was pretty disgusting. When I was lifting my XL, one of the astro guys suggested rhino lining or some kind of protection for the underside of the wooden floor - not a bad idea, considering how much of the elements splashes around down there.
I was out an event this weekend with big toys and toyhaulers, and no one had ever seen a Tiger before. Get ready for lots of questions, and welcome to the club