M_Boats: Access Hatches, M17

I want to be able to access my M17's transom gudgeons, motor-mount bolts, bolts through the horizontal surface and, in the future, swim-ladder bolts. Where should I locate inboard transom hatches? I figure I'll need at least two, perhaps three. I will want to locate the hatches symmetrically, for aesthetic value: How do I measure and cut the holes? Is the vertical inboard transom surface (liner) cored or solid 'glass? This will be my first spring project. Thanks!