I"ve bought, fixed up and sold more than 40 cars, trucks and vans. Been a hobby of mine since high school.
Sell and take the hit. Don't do the conversion.
When you're into a money loss situation with a vehicle, it's usually going to be a percentage. Losing 20% on 14k is less bad than losing 20% on 35k.
If someone else can look at a custom project and say, "well, I could do the same thing for the same price", then why would they want yours? They'll always think they can do it a bit better than you did, and they'll always find something about what you did that they won't like. Someone who doesn't do projects and would just pay for an already done custom is A) going to want perfection, and B) want a deal on it.
Yes, there is "the one" guy out there who wants exactly what you have and will pay exactly the price you want to sell for. The problem is that you might be advertising, and sitting on, that vehicle for a year or two before you find him or he finds you. It's not just about finding the right person - it's about finding the right person who wants the right thing and has the right money and doing all that at the right time.
Is yours the B with the head removed? (If not, just ignore this part.) Not to be harsh, but to be realistic - if so, for a resale that was probably a mistake. People who buy fully self-contained RVs are doing it because they are fully self-contained. If there is no bathroom, then all they see is just an overdone van conversion. Maybe that B was worth 14 with the head, without the head...who knows what the market will bear. Half?
When into a money loser (hasn't happened often, but it has happened), I usually would just rather move the thing, take the hit and get on with my life.