The walk through is critical to understanding the systems on your rig. This should not be rushed. For a new rver, with little experience it should take at least 2 hours. Take notes and have someone with you to record everything. Remember before you hand over the Benjamins you are in control. In my last purchase I had it written in the contract that I would return the coach in two weeks with a list and wanted to be front of the line. Did they like it, no, did they do it yes.
It also helps during the negotiations to have one of the party sigh and say "I think we should go back to _____RV and take another look at that______"insert name of simular rig.
Once they have your money most of them don't know you.