Hi,
Sorry to hear about all of the difficulties you have been having.
Just another suggestion: I think it would be possible for you to sue him in Florida under Florida's "long arm statute" because the property which is the subject matter of your contract is located in Florida.
This might work better for you for two reasons:
First, it would be more pleasant for you to travel to Florida than New Hampshire. If you can take your vacation there anyway and don't mind spending a little extra time to file your claim, this might work out well for you. If he does not respond, you will win a default judgment.
Second, when you seek to enforce your judgment you would need a Florida court to attach his property (
DVC) in Florida anyway, so might as well start there.
I hope he responds to your calls and straightens everything out so that you don't have to think about this anymore.