We did have a 43 ft "A" but was too much time and restricted our travel.. As for the list use common sense above all. I know you don't like the C because of the overhang but the B+ does not have that problem. What ever you do look at the following.
Look under the coach for hanging wires and clamps
On pipes etc (on your back and eyes open for anything that looks loose or out of place)
Try all doors drawers closet latches (look for easy use and smooth fit and finish. Pull the drawers out and look under and behind with flash light is it clean or is there sawdust trash extra screws missing screws etc.
Check all plumbing fixtures for stability (are they tight and firm or loose)
Check all electrical light switches and electrical components for good working order
Try all tvs stereo equip satellite or cable equip for operations.
Look at all trim for loose attachment, staples/screws sticking out look up at the ceiling and down at the floor for fit and finish.
Sit in all chairs seats and on the toilet for fit stability comfort.
Lay down on bed as if you are looking to buy a new mattress.
When you open the outside basement doors look at all hinge and opener screws for fit and finish and ease of closure. Open all access panels in and out of the coach and inspect for trash bad connections loose clamps etc. again use your eyes, ears, hands with a flashlight. Does everything look right, it that the way you would expect it to be done?
Try out all appliances Stove, microwave, etc. where reasonable.
Open and try all ceiling vent units, do they work, open and close smoothly, run quietly?
Get up on the roof and inspect all of the seals etc.
Inspect he chassis and body for fit and finish paint quality etc.
I think you are getting the point. Each unit is different and each manufacturer has its own process. It is up to you to prove the unit worthy of your money. Don't be pushed into buying a coach until you are absolutely happy with all aspects.
The guys that sell these make a good commission to get you to spend that money. They work for the dealer. Make them earn that commission and make sure all is to your satisfaction BEFORE you sign that contract or at lease a list of the repairs/updates required signed by the sales manager is in your hands.
Also, if you are buying a coach with duel rear wheals make sure it has valve extensions installed for all six wheels. You don't want to be crawling around on your back trying to check tire pressures in the wet or cold
Insist that the following be included in the sale after you negotiate the price.
Tire valve stem extenders
Sewer hose and connectors
Fresh water hose
Roof top vent covers( so you can leave ceiling vents open in the rain)
Anything else you think you might want to get them to close the deal.
It is the time of the year when sales are very slow. Our unit had a list price of $122k we negotiated the price down to $84k from their asking price of $98k. And bought the 3 year extended warranty. Do NOT let them sell you the interior and exterior paint treatment as it is a waste of money and you can pay someone a couple of hundred dollars a year to detail and wax your coach. I hope this is helpful, but the main point is all of this is easy
before the sale and
IMPOSSIBLE after.. Go on line and look at the "special" pricing across the nation for the particular coach you are looking for and use that as the basis for your negations. Even the special prices can be negotiated down..