I’ve been woodworking for many years and have used circular and jig saws to follow lines to cut wood but sometimes I just want a little extra assurance that my cut will be a good one. So when it came time for the doors, I tried to use a straight edge whenever possible. The challenge is clamping it to the shell of the camper to follow the lines of the doors. Here is one way to do it that could work for many of the lines. Another post shows how I clamped a straight edge on the opposite side of the camper. That way won’t work on this side (for this line anyway) because the clamps would be in the way. Here is a link to that post:
I started on this side by partially cutting out the window to make room for clamps. Then I realized they would be in the way of the saw and ended up using double sided tape to hold the straight edge – for me a long piece of aluminum that I’m planning to make into a roof rack for the camper. I only used two pieces of sticky tape and it held fine, just don’t push too hard against your straight edge. The masking tape is there to show the cut but also let me mark where to clamp the straight edge. It takes some time plus trial and error to set up but the result should be worth it, since the doors are one of the more ‘visible’ parts of the camper and you’ll see them pretty much every time you enter.