Here is a BB test joint I've prepped for the oven. I used 3 pieces of Stretchlon 250 bag material and 350F rated bag tape. Under the tape is release cloth with a very fine weave, then the carbon prepreg layers. You can see the UHMW plugs I use in the BB to run the bag and seal tape onto.
It took about 10 minutes to get all the leaks sealed and I was able to pull 26mmHg on the pump. The bag did it's job and stretched nicely into the fillets. The release cloth appears to be enough of a bleed layer on a bag this small, everything was pulled down tight.