Yes, it is. I tried bagging some wet balsa, and it stayed wet a long time. I'd guess dope would do the same.
Carbon mat works fine with epoxy in female molds. If one covers a flat stab with mat and dope, then puts it between two pieces of glass with some Teflon film betwixt stab and glass, how long would it take for the solvent to find its way out? Maybe Z Poxy would be a better matrix.
Howard the Zpoxy is a better way to do that, but dope it first, dope the stab with the dope fairly thick, brush out and sand with 4-600 when dry, just enough to knock off the raised grain, then put on a coat of Zpoxy, it will take a tiny amount of the epoxy to go over the dope sealed stab, I do this with foam wings and it takes only 1/2 ounce as compared to the 2 ounces it takes of unsealed wood.
Once the 1 coat of Zpoxy dries, you can then put dope over the ZPoxy to seal of and fill the CF Mat.
Work well as I use that technique for all of my wings stabs and sometimes flaps.
I also have the good stuff here, in both .5 and .3 weights
Randy