I laid the first layer of pro finish carbon into the moulds while they were speareted... and also a few of the following layers but clearly I left the joins in different possitions.... I then bolted the mould together and finished off on top of the existing layers fully but didnt need to be quite as careful to get weave perfect.
Of cause the issue you will also have is how do you smooth the bag out in this section as well... you need to be able to reach with your hand or risk voids on the bag anyhow.