I wouldn't go with a class B. It will be tight for the two of them. She'll have to set up the dinette bed each night and he won't be work after she's in bed.
Look for a class C 24ft if you want a motorhome. It will be big enough for a dry bath (shower, sink and toilet) and will have two dedicated beds if you get a cabover bed. In addition, by putting curtains over the cabover bed, she won't be distracted by his computer light at night. He will be able to sit at the dinette working while she sleeps in the cabover. Yet it will be small enough to park in most outdoor parking lots (he won't be able to park in parking buildings most likely).
Also, at that price point, he will need to be handy with engines and be able to learn RV systems so as to maintain, repair as needed. Otherwise it can get expensive. And at that price point, there will be things that need repairing right off the bat.
