Anxious in the sense of someone trying to scam you? Someone wanting to "case the joint" to come back and steal it?
There are basically three options available to you, in descending order of risk and descending order of sale price(!);
1) Sell it privately and "directly" - you can mitigate some risk by choosing to meet somewhere neutral (e.g. a petrol station - plenty of cameras) and payment can be made by either bank transfer or PayPal (former might be limited by the bank, but you can see more or less straight away if it's landed)
2) Use an intermediary; I used "carandclassic" to sell my classic motorcycle as people turning up to "case the joint" is common with bike sales. With that platform, the buyer agrees a price with you, they transfer money to the intermediary and they come to look at the vehicle. If everyone is happy, the sale is confirmed there and then and the money is released to you as the seller. As the buyer has to stump up the money up-front, it's much less likely you'll get anyone trying it on (or anything more sinister)
3) Sell it to a dealer specialising in campervans - they take all the risk, but you'll pay for it by having a lower offer. Biggest advantages are you can decide when and where to sell it, rock up, agree a price and throw them the keys - job done. If they're not massively remote, might be worth contacting the original converter too - they might offer a better price potentially, assuming it's not a DIY conversion?
It's the same old story - risk/reward - you take some of the risk and you'll likely get a better price, if you want to discharge that risk, you'll pay for it.