Koi-Lo wrote,
There's soil under the floor
where I want to put it (large dining-room) so jacks aren't going to work to
support the floor unless concrete footers of some kind are laid... too much
expense and it's only a crawl space. ........

The ground in your crawl space doesn't freeze does it? Just put a
concrete patio block on the ground and shore up from there. If the
ground doesn't freeze, it won't move up and down - no need for a
footing............. Frank