Will there be any significant loss of strength if I don't fill the weave on the inside of this build.

Les:
I hope not, because I hardly ever do a fill coat on interiors!
I think you will be fine without a fill coat.
However, the boat will be easier to keep clean (especially if you have a lot of fine sandy areas) and more wear-resistant with a fill coat.
Without a fill coat, it's less slippery, which can be an advantage sometimes.