Unless you are going to file Chapter 7 Bankruptcy, my suggestion is to NOT let the RV go to the bank to be sold. Drop the price more and then make up the difference to the bank, so the loan can be paid in full.
Otherwise, the bank will report the event as a repossession. Your credit reports may or may not note that it was voluntary, but the impact on your credit will be the same. In reality, RV sold at auction do not fetch as much as you can get privately, so you will end up with a larger unpaid balance to the bank, which you may end up paying or they may take you to court on a collection action.
If you bought the RV at a dealership and financed it there, then if the bank fail to give you the notice required by California Statute, they may not be able to get any extra money from you after they sell it at auction. These are standard forms, but sometimes they use old forms or the forms contain errors, which may get you off the hook for the unpaid balance, which is known as the deficiency. Not many attorneys are aware of this, so you need to consult with a consumer attorney who has successfully dealt with the vehicle finance forms. In addition to my link, I have provided a link to the National Association of Consumer Advocates, so you can search for a member in your area.
It is possible that you can negotiate with the bank about credit reporting issues and the balance owed after the RV is sold at auction, but my experience is that they will report it as a repossession and are somewhat limited on how they can report this event. Better to be ready than to be surprised months later. If you have other debts, you may want to explore Bankruptcy with an attorney in your area.