"Anyway, what I need advice on is how to sell the unit without the title in my possession."
Your lender lent money to you and your DH because they trusted you and your DH to pay them back. Now you and your DH have decided to sell it to someone else that your lender doesn't know...doesn't trust. In my state you have NO right to sell your vehicle to anyone without the lender's permission or paying off the lender before the vehicle is sold...you don't "own" what you are trying to sell. Working with your lender you can sell it.
No one legitimate, no one, will "buy" something from you that you don't own. Careful, again here in our state, it might be considered theft to sell what you don't own because it might hurt the lender...the "real" owner until you pay them off.