farken noice! You could cut the wheel well out then brace the rear chassis and new floor sheet. A bar behind rear seat and another bar above might help stiffen the centre a bit behind doors and would go unnoticed with a dog cage style thing attached.
i have a wagon and I check this thread frequently for.inspiration. I dream about doing something like that to mine thought I’d share. I would like mine as maybe a hillclimb car or something eventful.
Thanks for sharing love the pics. Red is a wicked colour