Finishing/Refinishing Problem

A friend of mine - - really, it's not me - - has a real paint problem. Following an article that appeared a while ago in "Model Aviation", he finished his plane with latex paint clear-coated with water based polyurethane.
He uses 15% nitro fuel. After the first flying session with the plane the finish got very sticky; no lifting or peeling, just sticky. After a thorough cleaning with alcohol and a couple of days of drying he decided to try clear clear Krylon over the existing finish. The clear Krylon dryed OK, but after the next flying session the finish was sticky again. After a thorough cleaning with alcohol and a few days of drying the stickiness was reduced, but it did not disappear.
I have suggested to him that, after testing for compatibility, he try Varathane Diamond Wood Finish, Chroma Clear, or Klass Kote epoxy as a fuel "proof" clear coat.
BUT, what should or can he do to prepare the existing finish to receive the new clear coat without risking either curing or adhesion problems?
Your suggestions will be very much appreciated.

In the thread about K2R spot remover the use of a paste of alcohol and cornstarch or alcohol and talc is touted as being effective in removing oil. It occurred to me that several applications of such a paste to the entire ship, combined with light sanding between applications, might provide the kind of preparation necessary to provide a good base for whatever fuel "proof" clear coat is chosen. However, given my lack of expertise, I would rather not recommend this to my friend without some support from more experienced finishers. Thanks. Your suggestions will be greatly appreciated.

Well, now. We're kinda' short of facts. If the experimenter copied the materials in the magazine article to the letter, then it appears that the author left something out that the experimenter should have known about.

If the experimenter used 'just like' materials, he was playing in the street.

At any rate, the soundest and quickest fix to the situation is to remove the nonperforming finish entirely and replace it with somthing that the builder knows, from personal experience or experimentation, will perform as intended.

I have never known clear Krylon to be alcohol fuelproof, or even alcohol fuel resistant. As for the previous clearcoat, laying a coat of anything on ain't the same as being certain that it is not porous and allowing the nasty fuel and exhaust to penetrate into the latex....