Nice thought, CD, but I think you were beaten to it.....
Sir Ranulph Fiennes did seven marathons, in seven days, on seven continents after a double heart bypass. Don't suppose he had trouble getting his expenses covered.
The problem with feats of aviation is that the sums of money required to actually do them tend to dwarf anything that might be left to give to charity. If you are young, inexperienced and don't own an aircraft it will be quite tough to get the basics in place.