When we start this " hobby ", if we all worried about depreciatation, nobody would have an RV!
If it is too much of a draw financially, then sell it, but I wouldn't even consider buying another unit. The depreciation on the new truck and trailer combined will make the DP look like chump change.
If you feel you can't use your DP enough to make it worth while, do like someone else suggested and sell it. Put the cash away to use on a nice vacation every year. When your work situation changes in a few years, then you can reevaluate.
Do a little spreadsheet on how much it costs yearly between taxes, insurance and maintenance, and compare that to a nice week long vacation somewhere you would like to visit.
If you do decide to keep it, I wouldn't worry about the 10 year mark. DP's are designed to last a heck of a lot more than 10 years. Now with the " improving economy " ( yeah right ), lenders are opening credit back up and there are companies that will do loans on units over 10 years old. Then, there are always cash buyers.
Best of luck with your decsion.
Cheryl