The shower thing is not a big deal to me. If we are out for 3 days, we usually take 1 shower. So it's not that big of a priority for me to have it inside. I rather have my storage space and big bed.
James, here's a few of the biggest reasons why we like our SMB over the AT/RTT setup.
Park and camp. No setup. Everything is ready to go. Just pop the top, you're done. You don't even have to get out if you don't want too. This is good for bad weather, rain, snow, mud, etc. No huddling under an awning or inside your rig/tent until weather clears.
Same goes for packing up camp and leaving. If you did the above, in the AM you can make your coffee, lower the top and drive out. No packing up a RTT and putting the cover on, no hooking up the trailer or putting stuff away. Just fire the truck up, lower the top and go.
Privacy. Nothing like waking up in the AM and wondering around inside in your under garments, grabbing a cup of joe.. reading the paper.. using the porta potty... what have you. Same goes for when you want to head in for the night. You can get away from the group and relax on your own inside if need be.
Fridge and food access..... midnight snack? You don't have to climb down the ladder and put your shoes on to grab a granola bar. I drink water when i sleep, if i run out i just grab another out of the fridge. Simple, in my socks.
Bathroom is inside... sometimes you don't feel like going outside in the middle of the night, it's freezing, or it's raining... it's right there and ready for you, inside.