Thanks for these suggestions. I made some changes to my ad. I'm still considering the financing - it seems safe enough but it could become stressful. Maybe I could consider with a club member.
The real stress is on the buyer, if you write a sales contract which specifies when payments must be made, what the minimum payment must be, and that all money is forfeited if a payment is missed beyond a certain time frame. Who knows, you might end up with half the money AND the airplane!
I've done this with houses and it works beautifully. The trick is to get a really good attorney to write the contract, which the buyer pays for since it's a convenience for him. States have different laws regarding what has to be done in what amount of time. If you agree the monthly payments have to be on the 1st with 10 days maximum before it all defaults, even if you agree in a contract, some states might say that you had to give him 15 days and when you go to Court it all gets thrown out and you end up losing. These types of sales work but with a good attorney.