DD,
Are you going to access the sink/stove from the back side of the camper (ie be standing in the doorway)? Otherwise there isn't a whole lot of space to belly up to it so to speak (at least it appears that way).
Also you're going to want to do something about the table/counter to be able to get into the front dinette seat (or have the table move to let someone into that seat, assuming you want someone to be able to sit there). I was playing around mocking that up with some scraps in the garage and for me it seemed like I'd need 12-14" min side access to slip into a seat that the table over hung in that scenario. If the table was narrower and allowed you to stand in the gap between the table and the seat my sized build would need about 8" clearance between the two. Let me know if that doesn't make sense.
Think about how to step up into the bed when that table is in the way (might not be an issue if you scale back the counter to allow access into the blocked dinette seat to address the previous comment).
That's what I got off the top of my head. You've got a lot more flexibility in design working up more of a 2 person setup. How long/wide are you thinking on the main camper? Ever have any desire to be able to put bikes/skis/etc. inside the camper on the floor?
This stuff is fun/exciting.
As a general question: Does anyone know why campers have the appliances and propane tank on the driver's side of the camper? If I did it I'd put that heavy stuff on the passenger side to better balance the whole rig -- since the driver's weight is always going to be on that side while there's not always going to be someone's weight in the passenger seat (almost never in my truck).
Or do some brands of camper not have the heavy stuff on the driver's side?
I'm keeping the appliance over there just because the counter space works but if you look at my mock up I'll either try to put my propane or water tanks under the fridge on the passenger side front of the camper.