Finding a best deal formula for trade and buying

No such chance and if you are trying to upgrade and hope not to take it in the shorts, good luck. Whether you paid cash or financed your current rig, trading it in will always be a losing proposition although the dealer can make you think you got a good deal, at least that's what he is shooting for. Choose your next RV carefully to reduce the chance of repeating this scenario. Enjoy your new TT!!!