Just a few thoughts. We just went the other way from a Sprinter B to a class A. Reasons? Several. Probably comfort was the biggest. If you want to stay in one place, a B gets cramped quickly. Ours had no insulation (Winnie ERA) bad was impossible to keep comfortable on a cold nit in the mountains. Maintenance is less on a B but not that much less, especially a diesel and they still use the same appliances and have the same caulking issues. Working underneath is nearly impossible, a A has much more room. Bath was fine but black tank was way too small.
Just a thought, maybe consider a small A or C with or without slides. Maybe find a local RV tech or general handyman to do the maint at a reasonable cost on the side after hours.
I would suggest trying a B rental before buying if you can. As a retired auto mechanic I am now resuming minor maint on our A because of room to work, work I had stopped doing on the B. BTW, I am 71 a stroke survivor and not able to do everything I used to but have found an A actually easier in some regards.