Nice! We were faced with the same thing with our sixty lb dog. However, our RTT is mounted on a trailer and doesn't sit as high as yours. We got a doggie ramp and installed a bracket to clip it to the top rung of the ladder, and propped up the lower end so the ramp is not too steep. After 3 outings we leave the ramp set up after getting out, and our dog goes in and out on her own. Here is a pic of our setup.
There is a lot of wildlife where we usually go camping (bears, wolfs, Moose) I would never let my dog sleep outside for safety reasons, The dog love the RTT, it's confy and she's with us. She's used to sleep with us since we have her, so I guess we kind of create that needs for her.
For years, I would carry my 100lb Ridgebacks in my arms as I climbed the stairs into the RTT. Eventually they got the hang of it. My GSD always likes to sleep on the ground or in the cargo area of my rig, and he is 110lb. I just ditched my RTT and returned to a ground tent (Marmot limestone 8P) and, to be honest, am so much happier with it. The RTT served its purpose in my life for about 5 years but I really wanted to be able to “go” whenever I wanted when camping out in the bush, and more importantly, be able to walk in and out (and stand up) in my tent. Now I can fit two queen size mattresses in my tent, plus sleeping areas for my dog with room still for an interior sitting area. And I save about 100lbs from no longer having the RTT.
It's my first season with the RTT, so far so good with the night and morning routine for the dog, but mine is not as heavy as yours. I never had a tent that I can stand up in it, so I'm used to it. Nice truck and beautiful dogs