There's all kinds of security devices out there. Cables on a reel that bolt to the frame of the TT.....etc. I have a topper on the truck. It, as well as the tailgate both lock. But of course, I don't always want to carry it around if we need to run to town or something. Often times I'll put it under the tongue of the TT and run the safety chains through the tube frame. Then a good padlock through the chains. Our new TT will have a generator rack on the tongue. I'll have to figure out a way to secure it there.
As for sheltering.......if it's running, I usually don't want it right next to the TT. But if it looks like rain or nasty weather just set it under the TT. Try to pick a location where water won't run down hill right to the generator. Remember to point the exhaust away from the TT.
:B 2013 F-250 4x4 Crew, 6.7L Turbo Diesel, 5000lb Air Lift rear bags,
Equalizer 1200/12K Trunnion Bars
2015 KZ MXT 303 Toy Hauler:C
2013 Yamaha FJR 1300, 2 dogs, Him & Her:C