Just a thought Neil. Would it help if you make a wooden partition that "sits" on the fuselage deflecting the hot air from the wings. Then remove prior to flight departure. The wings should be cooler than as when flight takes place the air and propwash should dissipate the hot gases. Re-apply when the plane is again stationary.
As an aside, I often wonder what is the side and downthrust on these planes? Judging from the photos there seem to have quite a deflection.

Reuben