Your're in Florida and have the benefit of a very favorable land trust statute - you may be able to use it here.
Place the property into a florida land trust with seller and buyer as beneficiary's. Also prepare a conditional assignment of beneficial interest with the condition being that upon evidence the loan will be satisfied (payoff on HUD) the sellers interest automatically assigns leaving just the buyer (you?) as the only beneficiary. You could also put some reverter language in there saying that if loan satisfaction doesn't happen in a certain amount of time the buyers beneficial interest is voided and the property reverts back to current owner.
You could also use a wrap around.
In any case, you need to review the due on sale clause in the current loan docs to make sure you aren't going to trigger anything.
As for the unlicensed practice of law, anytime you draft legal documents for anyone other than yourself (or a transaction of which you are not a party) you are practicing law- UNLESS you have a license approving such servicces. Real estate agents are allowed to draft things like contracts and addendums for transactions where they represent the buyer or seller. However, I believe a deed, mortgage or note would fall outside the scope of those services realtors are licensed to provide.