The first thing to check is the mounting ledge under the front window. Make sure it is still solid and tightly attached to the shell, no wiggle. Given the age of your Scamp
, front window leaks
in the past may have allowed water to get inside the fiberglass and rot the wood, so inspect carefully. In this picture the ledge is the rat-fur-covered piece that the hinge screws into. This is looking up from under the bunk. Notice that the ledge carries the weight
, so its integrity is critical. The offset hinge just holds it in position and allows it to pivot to the backrest position.
The upper bunk platform is 3" foam glued to 3/4" plywood. Upholstery goes over all. The plywood is three pieces, one large center piece and two small wings attached with piano hinge on the foam side. The wings allow the bunk to conform to the curve of the shell when lowered.
I vaguely recall someone may have posted a link to a template for the pieces of plywood, but I couldn't find it. Maybe someone else can help, but if not…
You can make your own template from cardboard. Use the bottom seat as a starting point. That should get you very close. Make it a few inches wider (front to back) to start so you can fine tune the curved edge. Put the piece of cardboard in place where the upper bunk goes, resting the front on the mounting ledge and propping up the other end. If it fits, great. If you need to adjust the curve for a better fit, lay a piece of garden hose on top of the cardboard pressed tightly against the front curve of the trailer. Trace along the garden hose on the cardboard. Cut the cardboard on your traced line and it should follow the trailer's curve very closely this time.
Now tape the template to the mounting ledge from below so you can fold it down to make the backrest. When in the dropped position, the upper bunk should rest against the fiberglass of the base (behind the main seat cushion) about 3-4" out from the front wall (the banana cushion stores behind it turned on edge) . Cut down the width of the bunk template so that when raised it is even with the front of the seat base and when lowered it rests against the seat base close to the wall. Looser is better than tighter because foam and fabric will add to the dimensions later. Rough guess… allow a gap of about 1/4" - 3/8" all around. As you do this you will need to fold the wings (using the attached pictures as a guide) to get a good fit to the curvature of the front shell.
is pretty helpful and you'll recognize some of the pictures.
Hope some of this helps!