You don't say what type of vehicle you have? Do you already own a truck? Truck size will dictate the size of camper you can put on the truck. A small truck will be a small camper. Getting up into the large trucks like the 3500 long box duelly will give you more options on the type size and models of camper.
Access and egress out of a camper can also be an issue. The Northern Lite camper we have has large stairs which make it easy to get in and out of.
Other campers have different types of stairs so do t just try getting in and out of the bed see how your going to get in and out the door as well.
Northern Lite Stairs scroll down the page to see the stairs.
You say you dry camp a lot, so these dry camping areas have washrooms? Camper bathrooms / showers are usually smaller than other RV's so that's something you should also be thinking about if you have mobility issues.
You may want to think about a small class C unless you already own a truck and your trying to cut costs.
Soup.