That is both, a great build and first race experience! Sorry you had that door mishap, but from here it looks like you´ve got the perfect skill set to fix it. Beautiful car btw!
There is a walk around of this car starting at 14:08 in Mart's video of this meet, as well as some background shots later on. Was the trunk lid removed for the first run? https://www.jalopyjournal.com/forum/threads/pendine-sands-2025-from-soggy-to-sublime.1341845/ Around 40:30 and 51:00 show more including after the second run with the door coming off.
The trunk lid removed itself the first run! There is a drop in the dunes along the beach and a crosswind hits at that point if the wind is in that direction which is the same point the door was unlatched. both the doors and the trunklid are un reinforced fibregl*** and extremely flexible. Hence why when the body was on its previous race car they were purely cosmetic and glued shut. But it is in our plans this winter to install new doors with full inners to add some rigidity to them and convert over to bearclaw latches. the perils of a belly pan, it stops most of the air getting in, but whatever air does get in then wants to get out too! And finds the quickest way!