Actually, not hard to fix and I have done this on three boats.  I use the CLC hatch kit on my strip race boats but hatches are too wide to fit in narrow boats.  I modifiy the hatch kits by cutting an inch or so out of the sill in the front and back, then butt join them together to mare a more narrow sill.  I then cut the spacers so that they fit on top of the sill as they should.  Then, I use the modified spacers to ouline the hatch cover before cutting it out. 

What I am suggesting is that you keep your cut out hatch cover and modify the sill to fit.  If you cut 3/4" from the 3, 6, 9 and 12 o'clock positions, then glue it back together, you should have about 3/8" of a ledge for the cover to set on.  Now that I think about it, It would probably be just make a new sill if you have any extra Okoume laying around.  You will alos have to make/modify the spacers.

Picture below is the front hatch on my Yukon.  As you can see, it is much narrower than the standard forward hatch. 

Ask if you have questions.

   Thanks for that.  That was also one of my thoughts. then just living with a smaller hatch. By making my own sill and spacer I can save on space and free up some opening width.  

Thanks again for the quick response