1 layer of 1708 is between 0.044" and 0.052" thick depending on how good your resin/glass ratio is.
Here is the Original deck schedule for early ‘70s 23’ Sceptre; top to bottom (from Feb ’73 Boating, Boat Test #207)
1 layer 3/4 oz mat
2 layers of 1 ½ oz mat
1 layer 22 oz roving
1 layer of 1 ½ oz mat
3/8” end grain balsa
1 layer of 1 ½ oz mat
1 layer of 22 oz roving
The top skin was originally ~.195" (not counting gel coat) and the bottom skin was ~0.080" depending on r/g.
Most of what was in the top skin seems to have been for durability/damage resistance rather than in-plane tensile strength.
You might want to think about a bit more than 2 layers on top and 1 layer on bottom.
