Steve,
I have been using Randolph's Nitrate since Bobby Hunt turned me on to it in 1993. For all substrate, and attaching CF veil, silkspan, silk, Jap tissue, or polyspan, I use the 'Non Tautening Tinted" which Bob recommended. It thins with Dupont 3608S, no problem.
http://www.aircraftspruce.com/catalog/cspages/randnitratenontaughttinted.php I go to butyrate dope to shrink and fill. My last Classic plane used no filler at all. Just tinted "n/t" Nitrate. Very light, and it filled all the grain, etc., as good as using a filler.
Do NOT buy it in gallons or more, unless you plan on picking it up yourself.
Buy it in quarts. It is more per quart compared to per gallon, but the shipping is about 1/10th the cost! For whatever reason, the quarts do not have the extra charges tacked on that goes with gallons or more. The extra dollars will be made up many times over in the erduced shipping cost. Plus, you can open a quart at a time. This was from Aircraft Spruce, directly. Get a quote from them about this.
Oh, yeah, covering is easier to apply with nitrate, it is "stickier'! That IS the truth!
This was a "nitrate base" plane, no filler: