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Most TC's now have 4 jacks, which can have extensions added as an option.

Buy extended plates and add to the camper you choose.
Or you can manufacture them for 1-time use, what considering the flatbed width might be the only option.
There is no easy way to load the camper without original jacks, especially considering that you plan to buy older camper where structural integrity might be in question.

Not sure, but thouhg it would be really tight and wouldnt attempt, our camper is 92 1/2" between jack tubes without extensions. Point being if looking at particular camper might get a measurment between tubes.
On our Atwood jacks simple pre drilled flat bar placed between jack and camper plates would be easy to gain addtional width. Assuming flat bed dont need swing away mounts.

Seller deliver?