5th wheel...TT...which hitch do you have?
We don't even know what you are using to tow with!
Chances are you can use it your with the new RV, but we really can't give you an answer as you'll need to have it all adjusted for your specific setup.
Just take it all with you and let them (dealership) adjust it all while you are doing your very extensive and in depth PDI.
And if you need more hitch...get them to throw it into the deal somehow!