[michaely]

I used Sig Supercoat clear butyrate (presumeably with more tautening power than 'Lite Coat') on a quarter scale model that is still around after 35-40 years and did not experience any warping of the structure nor is there any cracking of the finish today.

I recall that I added a "plasticizer" ... pharmacy grade castor oil in the amount of perhaps 5 drops per quart....... Dave Brown had a similar product called FlexAll that people also used. The plasticizer was used to prevent cracking of the finish over time, but others have said/claimed that it also reduces the tautening power of regular nitrate or butyrate dope.
It may be worthwhile calling up Randoph or Brodak and asking them... and others hers here may have an opinion on this.

The control line crowd websites and blogs would be further sources of information.

good luck,

Michael