One of the first things I did to my 13' Scamp was add access doors. There was no way that I'd be lifting the couch/dinette and/or bed cushions to access the storage areas.
Like Patrick said I first put an access door just inside the entry door on the couch cabinet. I simply ordered a door from the factory along with all the hardware. The door is the same as the overhead cabinet doors above the sink/stove.
I put an access door in the street side dinette cabinet, no need on the curbside as that's taken up by the fresh water tank. Any way, in the 13 footers the electric convertor is in the forward area of the cabinet so all I was trying to access was the rear section of that cabinet.
I first put a divider in the cabinet not for seating strength but simply to divide the space so nothing I stored would hinder the electric box and cord. I just jammed a 1/4" piece of plywood in so it acts as a divider. Then I figured out where I'd would want the door, took measurements, called the factory and ordered the door plus hardware. This was a special order door so they charged a little bit more for it, but was reasonable.
I leave the dinette down as a bed and store items on a tray that slides out. I found that the cabinet door was troublesome so I've since removed it. Now I just reach back into the cabinet for what I need. Sometimes having to remove items from the tray in order sort of crawl back under the bed. Obviously the items I store there are ones I don't use often. For example, I will put extra toilet paper, paper towels and dog food back there that I'll need on my 2 1/2 month Alaska trip.
The 13' footers have angled walls next to the closet and the kitchen cabinets on dinette benches. I cut holes in those angled walls, ordered doors from the factory along with hardware. The door next to the kitchen cabinet allows me to reach in and untangle the electrical
cord. The door next to the closet allows me to access the fresh water drain valve, plus I found there's a little storage area there. Be careful what you put in it as you don't want to have anything rub the water tank causing a leak.
Then the only storage area that I couldn't add a door to is the one on the street side of the couch.
I simply opened the center door and cut a hole in the divider. Problem solved.
No need for me to lift any cushions to gain access to the storage areas of my 13' Scamp.