even if that huge patch of filler doesnt crack and drop out, its going to sink and look terrible very very quickly! surely must be a better option, either the 1 piece door suggestion, or maybe make up a complete flat skin for each door, so it wont have huge sections of filler that risk cracking or sinking?
also, i genuinely thought this was a wind up thread too

the pic of u trying to put the side of the van in primer with a small spot repair gun with the tiny cup on it is hilarious! would take hours to do just 1 side!