Yes, one good battery can suffice in normal situations, and a dedicated deep cycle battery is a better solution when you have need for house power.
I like the option that Chevy introduced last year to have dual batteries that are isolated, it would be helpful to have those.
For me, the gobs of power with dual batteries means that I haven't worried for years about leaving anything on too long and so far have not had a need for separate power which is more involved and costly than having 2 starter batteries under the seat that power everything.
And
@thecho if your single battery is good you don't have to replace it with two identical ones, though I prefer to have matching batteries so there is no doubt about one being older/weaker than the other. Some of our electrical wizards could provide better technical information on that.