Can I deduct the loss of our second home sale, which is an RV. We live in this full time for work and rented our primary residence?

The loss on a sale of a personal residence, not used as a rental or in a business, is not reported on a tax return.  Unless you received a Form 1099-S for the sale, then the sale is reported on a tax return with either a gain or a loss.

@DoninGA does this apply if the purchaser sent you a 1099-MISC for the sale?

According to this IRS link, A loss on the sale or exchange of personal use property, including a capital loss on the sale of your home used by you as your personal residence at the time of sale, or loss attributable to the part of your home used for personal purposes, isn't deductible under any circumstances.

@Kimmie18