Seems to me that making holes larger is much easier than making holes
smaller.  However, the formed region in the top may not accommodate a 14"
square.  Try matching a piece of cardboard that is the exact size of the
hole required to the area on the roof.  That's a camper top roof to which I
refer while dodging dangling participles.

REF:

Date:    Wed, 17 Sep 2003 13:53:22 +0000
From:    David Maurio <maurio11@COMCAST.NET>
Subject: Skylight modification question

Has anyone enlarged the opening where the skylight is to install a standard
RV
14"x14" skylight?  Is this even possible?