Receiving the door frame reinforcements at the same time as the interior kit has resolved the door support dilemma. Enough with that super sophisticated door strut mod, I'm going with Europa Factory Mod 66.
I put the reinforcement piece in place and marked the limits. Scuff sanded the area covered. Mixed a batch of Araldite and added some FLOX. Applied the mix to the inside of the reinforcing piece and stuck it to the door frame. Then every clamp I had in the shop and house was applied to hold the thing as tight as possible. Removed as much of the excess Araldite as I could.