I called the Poly Fiber people to ask them about the Poly Tone. The employee I talked to said that the one-part Poly Tone has limited chemical resistance. When I told him that I wanted to use it on model aircraft that use methanol/nitro fuels he advised me not to do it. He seemed to be knowledgeable about dope and other finishing methods and he did not think any of the one-part finishing methods would produce the desired fuel resistance. He claimed that even gasoline (av gas) would attack the Poly Tone to some degree if not washed off quickly.
The two-part systems from Poly Fiber are the products he said would provide the chemical resistance if you wanted to go thru the added hassle of using these types of products.
I suppose one way to find out for sure is buy some and do your own tests.