"Is an SMB too much for me?" The answer is yes. An SMB is too much for anyone. We pay as much for these luxuries as we do for actual homes in some cases.
Does that mean you shouldn't? Not at all, but I do agree with above. Rent, borrow, experiment, etc. first. If your wife and especially your girls don't get out camping soon then they will likely never take to it. Here's our history:
$1500 pop up
$3k pop up
Cheap moto van to sleep in (camping trips or enduro/hare scramble/other moto racing)
bigger hard side trailer
30' class C motorhome
1973 Airstream restoration project with big pick up
Then vans.......5 or 6 including a couple SMB's, class B, yada yada.
Now, here's the important part of all of that. Keep in mind YMMV. My kids camped and travelled with us extensively during summers for the last 10+ years. Now they are teenagers with cars, jobs, relationships and don't want to go........but it's in their blood. They'll be campers and explorers all their lives, they're just busy being teenagers. My wife and I just had two blissful weeks in CO and Utah totally off grid with a Toyota pickup and RTT. It's all we need to get to the trailheads and quiet places.
We have no regrets about jamming them in camper vans and getting them out in the wild when they were young. Sure, my wife loves a nice hotel but not as much as she loves a quiet meadow in the Aspens or by a mountain lake. No comparison.
Pay attention to the part above more than anything. No matter how you do it get out in the wild with your family and see if they take to it and then see how you want to upgrade the lodging and transportation part. If they hate it then put together a one man setup and go with your buddies.