I don't know how experienced you are with casting, but when I did my cast the vents on the far sides gave me some trouble. You may want to cut them off your base and cast them separately for a cleaner pull.
Yeah that is the major drawback to 'block' style pepping. Using rondo is a big pain. I suggest planning out batches for each area. I believe I used 5 different batches to cover the inside of the helm in about this order:
Though if you are planning on wearing and not casting, be careful you don't make the rondo too thick. I wasn't worried about the weight because I knew I'd be casting.
Also, great job! I guess you and I are the only two that have finished the build lol