OP here with good news. After very friendly conversation with dealer expressing our concern over the interest rate, they offered to restructure the deal by reducing the purchase price to an amount that would create monthly payments that fall to a level nearly equal to what we would have paid with our desired interest rate.
So the bottom line for us becomes a total purchase amount that we feel is right in line with the amount of risk we are willing to take for a motorhome this old.
We can't praise the dealer enough for their professionalism and understanding as we stumbled through the purchase process. We learned a lot from our mistakes on this one and will be much better prepared when the day comes to buy our dream machine for fulltiming after retirement.
Many thanks to all of you who responded to our post. The guidance we took from your suggestions was invaluable to getting the deal we could feel comfortable with.
