On one side I say take the old car so you won't have to worry about rock chips etc.
On the other hand the worst trip I ever took was my trip to Utah and I chose yo tow my Toyota highlander instead of my jeep and everywhere I wanted to go I could not and ended up walking because the Toyota had no ground clearance. So if I am going all the way to Alaska I am bringing the jeep.
I had sylvania silver stars I put in a couple years ago which were better than the stock ones but still not good. So a couple days ago I installed these www.amazon.com/Hipro-Power-5900K-Super-Headlight/dp/B003FPF22I
And they are much brighter
I don't recommend electrical contact cleaner , some contact cleaners make plastics and connectors on control boards brittle and may crack or shatter.
When was the last time the heater was used?
If it has been a long time you may need to clean burner orfice and or flame sensor
Other than that everything Old-Biscuit said in earlier post
I carry spare capacitors for the blower motor and for the compressor and just in case I also carry a supco start assist.
If you are changing the motors and motor capacitors you might as well replace the compressor capacitor as well while you have it apart, it is cheap insurance.
I towed a Toyota Highlander with a lube pump for a couple years and still have it as a driver and no problems at all. I would definitely do a lube pump again if needed although now I am towing a jeep so no need
I have a fleetwood 40x dp that I bought new and We had a few minor problems, only one thatbI had to take to the dealer and the others were little stuff that I took care of myself because I did not want my coach to sit at the dealer for a month to get the work done.
Love my Fleetwood DP and would buy another one
If this 5th wheel is new or newer it should have an energy management system that will shift power where needed and you can run both ac units at once on a 30 amp circuit, my ac units will turn on blower motor then bring on the compressor so the full amp load of everything coming on at once is lessened.