Every year or more often on my TT I cleaned the roof and applied Dicor Rubber roof liquid coating that also covered all connections and flanges to roof fittings using a long handle roller brush. For me it was easy and relative mess free. Sometimes it was just certain areas I felt needed new liquid roof. Also replaced any old caulk with best quality caulk to outside areas. Used a trailer shop to re grease and repack wheel bearings with synthetic grease and I watched them do it. Cleaned outside of trailer with a good quality RV wash/wax and did this several times a year in the shade.
Used only Maxxis trailer tires with never any problems in high heat and applied rubber protection liquid from outdoor marine and no cracking on the tires and also did this several times a year in the shade.
Spent a lot of free time checking and inspecting including ladder time. No major problems in many years. Stop using propane appliances a long time ago and instead went electric only with shore power and/or inverter generator. Most of it was fun. I went by a long list that is now somewhere in my stuff. Did not do this all at one of course.