I don't think you'd have a problem with the pro wiring it wrong if you show him in advance the 30amp RV wiring diagram! Explain to him, "THIS IS NOT 220V, IT IS A 120V "RV" PLUG, NOT A DRYER OUTLET!
Tell him, "this is how I want it wired and if you wire it for 220v you'll owe me some serious cash!
If you give the electrician a head's up, you'll be fine as many, many, have not wired the 30A RV outlet.
BTW, installed mine myself years ago with a bit of advice from this forum. I was lucky because we had a 220V dryer outlet on the other side of the wall that we would never use so I was able to take the 120V from there.
