Thanks for the supportive words guys, they're much appreciated
Not much progress this week, I'm afraid, due to family commitments.
I did manage to make the seal 'lip' for each door, though. They just need a bit of sanding and trimming to make them an even thickness and height above the door opening all the way round, then they'll be bonded in place, and they'll need to stand off from the opening about 5mm to allow space for the seal to contact the surface of the door under pressure but without completely crushing it. That will negate the need to have a recess around the doors to take the seal -
To keep it looking neat and 'factory' finished, I'm thinking that I need to find a way of using a seal that clips over the lip rather than a self-adhesive version. As there's quite a wide and deep gap between the back of the doors and the body I think I can make that work...
Hopefully I should have a better update later this week