My wife and I bit the bullet and purchased a new TT. We are in the process of outfitting it. My first mods/add have been adding a cutting board leaf and a rack for fishing rods. Also got a good tip on the forum for a toilet paper holder.
Ross an TJ MAXX are your friends! I bought a LARGE cutting board and now use it for added counter space when I place it over the stove. I use skidproof shelf lining stuff from Wally World to keep it and other things in the cabinets from sliding around while underway. I keep ALL my cleaning supplies (interior) in sealed packing containers (if you drive into the mountains, the change in air pressure forces the liquid out). Buy an air compressor (tankless). Buy some Y fittings and 90 degree water fittings. harbor freight has solid rubber wheel chocks for less than ten bucks each !
Purchase a hand held grease gun for your buddy bearings.