One thing I did different was to place the guide so that there is overhang on both sides. I cut one side with my circular saw, and the other side with my router.
That is a great idea.
Anyways, I think this project could have been done in one, fairly brief, post:
BEFORE YOU START: the thickness of the ripper guide, and especially the saw board base, will affect the depth of the blade and the thickness of wood you can cut. I found 3/4 stock a pain in the ass, so unless you're going to need it to put a bear down, I suggest using 1/2 stock. 3/8 might be fine, also.
1. acquire one (1) 2'x4' sheet of mdf/plywood/particle board.
2. measure (or even eye-ball) and cut a 6" strip off of it.
3. put saw up to main board, as if to cut a half inch or so off it. Mark the end of the saw plate on the board.
4. place ripper guide on main board at mark, factory cut end facing sawing side; glue/screw/staple ripper guide to main board.
5. place saw plate against ripper guide and saw remainder off saw board base.
For dual-use saw/router board:
4. from the above, there should already be room on the other side of ripper board; only screw ripper guide in.
5. make another ripper guide, and replace old one.
6. put router against ripper guide on that side, and 'rip that side to fit', too.