I've done several on different RV even did two entrance doors
Plywood and sometimes 1*2's (entrance doors)
Most are made with press board, which doesn't bode well if it gets wet
Assemble with A good plywood of the correct thickness and all is well
I can explain it to you.
But I Can Not understand it for you !
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Connected using T-Mobile Home internet and Visible Phone service
1997 F53 Bounder 36s