Pressure Treated Plywood?

[chumbucket]

Pressure treated wood in an aluminum boat is a no-no
The chemicals used in the treating process are very corrosive to the aluminum in tin boats. I also believe you are correct in your assumption that it will not hod the resin too well.
I think you'd be better off for your hatch repair with regular plywood over the pressure treated in terms of fiberglassing the hatch. You'll be soaking it in resin anyways.