haven't done this in particular but have done lots of fitting.

all the other ideas are good but a few more:

bulkhd template:decide on your desired angle, hot glue in some stops to this angle and place in any irregular shape pc of card say 1-2" shy of inside surface so easy to set up etc.(shape is immaterial) make 20 narrow(1/2") pointed pcs of card or paper say 4" long and glue them one at a time radially outward from the card to just touch the inner surface of the yak. more you do it better the shape reflects the section. if a stitch and glue - only need one to the inside of any angled joint. this is really easy and dumbass to do, even from a distance.

then pull out the card and make the b/h to the outside of the pces of paper, fine tune for fit and preglass/finish on the bench, and set up pump, breather or whatever desired.

then use jay babina's pre seam technique of hot glue(or ca or epoxy if wait) tabbing(say here a dab every 2 in or so) on seam tape all around the bulkhead while on the bench (cockpit side and hatch if desired - fold back tab side) and with a stick, hold in place against the still in place hot glued tabs. then with a wet brush on stick or foam on stick seam one side, let set up. on other side, break away or ht gun away the tabs and brush the seam tape there also.

both the template tech. and the seam tech. will simplify and speed the process.