Julian Thomas is due to be sentenced next month over the death of Ann Marie Green.
The Puy du Fou attraction would bring "genuine variety and ambition", the palace's CEO says.
Simon Appleby is sentenced to three years for paying himself using his victim's account.
Performing arts union Equity says Puy Du Fou will provide "sustainable, high-quality employment".
The site near Bicester would include four period villages and 13 live shows.
Headmaster Ian Mullins says it is "not financially viable" for the school to remain open.
The park near Bicester, would allow to visitors "immerse themselves in British history", plans say.
Rachael Blakey and her family were heavily impacted by flooding across Oxfordshire in September.
A "multi-functional space" will be built in its place with parking, applicants say.
