Buying a motor home is unlike buying a traditional property. A motor home loan is a type of auto loan and will automatically depreciate over time. Therefore, becoming upside down on a motor home loan is not like having a real estate property's value drop below the amount you owe. Negotiating with the bank when you are upside down on the motor home loan becomes difficult because the asset is losing value daily.
Get a reputable motor home appraiser to do an appraisal. The NADA Guides are a good starting point, similar to the Kelly Blue Book or Edmonds for other automobiles but focused on specialty vehicles like motor homes.
Compare the appraised value of the motor home to the amount owed on your loan.
Meet with the bank loan representative. Bring your income details as well as the motor home appraisal.
Explain that you are not able to keep up with the loan value based on your existing income. Request a modification of the loan reflective of the appraised value and your ability to pay.
Request a longer loan period if the bank is unwilling to renegotiate the value of the loan. If you are unable to meet the monthly payments, extending the loan through a refinance might be the only option.