Among the criteria for making a home office deductible is that the office must be used exclusively for business and only that portion of the home may be deducted. For example, you actually have a dedicated office of 200 square feet in a 2000 sq ft home you can apply 10% of the utility bills and using a depreciation table for value of the home taking 10% of that depreciation for business expenses. However when you sell that home you have to recapture that depreciation as a long term gain (assuming when you sell the home and allocate 10% of the sales price to the office the amount is greater than the depreciated value of that office, which will be the case if you sell your home for the purchase price or greater).
If the RV is your only home, the first stumbling block will be dedicating a portion of the RV to exclusive usage as an office. The IRS will likely disallow such a claim unless the office is in a separate room.
In my opinion, it would take a really unique business situation to make it worth the while for a full timer to try and make a portion of their RV a qualified, tax deductible home office.
