MSRP and Trade-in are easily manipulated figures. Difference is what you are trying to figure out. MSRP can be pumped up by adding dealer installed options such as "all season treatment" (wax job), and other nebulous things. On a unit many things can change the real value, 50 amp upgrade, 2nd A/C, slide toppers, etc. Dealers very likely will add, transportation, dealer prep, PDI, document fee, coffee fee, employ movie pass fee, almost the weekend fee, etc.
Personally my method of dealing, vehicle or RV, is determine the best price out the door. Make sure you clearly reference the OTD with NOTHING added. The dealer finance manager will also hit you up for extended service plans, tire plans, maintenance plans, internal financing, and any other financial add on to boost his commission. Skip all these on a new unit, ALL. Walk if he/she won't shut up.
After you have the OTD price, then discuss trade-in. You will receive a ridiculous low offer because they give less than loan value on trade value. If you want more trade value, then they adjust the asking price, or add fees. Difference is the key factor.
Investigate and arrange your own financing. Your local bank or CU might be the best rates, but not always. Let them run some numbers and see if they can beat your numbers. Surprisingly a few years ago the Dodge dealer was able to get a 5 year no prepayment penalty for less that 1%. I took that since my investments returned more than that. No since cashing in a 3% return in exchange for 1% interest.
2007 Itasca Horizon 40FD
2012 Jeep Wrangler Sahara
2015 Harley Davidson FLHTKL