How about a nut splitter? Nut splitter
Not sure how close the wood floor is though. If it's even a couple inches away, a sheet metal shield would protect it from a cutting torch. The higher heat (and quicker than a propane torch) is going to keep the wood from getting scorched if there's a sheet metal shield between. I have cut nuts off bolts with an OA cutting torch and was able to reuse the bolt if done correctly.

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.