Legal Question in Real Estate Law in Nevada

The options you list are mostly impractical. First, "assumable" mortgages are a thing of the past. Your son would not be able to assume, in the future, a mortgage you take out in your own name now. He would have to qualify - just as though he were buying the property from you - on his own to have the new loan solely in his name. Borrowing together places you on the hook for the mortgage in the case of any default and exposes you to any liability attached to the property if your name is also on the title, as well. Removing your name from the title later is simple enough, but the lender will not likely agree to take your name off a loan (why would they give up a second debtor to chase down?) and, again, will force your son to qualify for a refinance of the mortgage in his own name and on his own merits.

If you are confident that your son will be back on his feet in due time, you could take ownership, yourself, with a loan that you qualify for on your own. Then, you could enter a "lease option" contract granting him a right to immediately occupy and to purchase the house from you at some future date when he has established his credit, residency and job history to qualify for the loan to buy you out. The rent could be exactly what your payment is, so there is no gain for you, but recognize that there may well be tax consequences for receiving rental income - from any source, including your own son. An accountant or tax adviser can provide good direction here.

There are some incredible buys to be found in Las Vegas right now, so you are wise to want to help your son into an ownership position. Recognize, however, that you can seldom do something like this "jointly," then later convince the lender to transform it into an "individual" obligation. Almost invariably, he will have to (eventually) qualify for his own loan to retire the one you take out to buy the house. I wish you both well!