I'd contact Roger on C-Hawk to find out what he used. His is a 22 C-Dory.
Journey On, in which I installed rectangular ports is a 25 and you're talking about a 22. So, all I can do is tell you where to get a porthole whose height is no larger than the Vetus.
The Vetus PQ51 porthole has an OD of 158 mm (6.32") and a cutout of 126 mm (5.04"). So any rectangular porthole which has an overall height no more than 6.32 should work.
Here's some suggestions. The
Bomar 2000 series portlight N2311-OVhas overall dimensions of 368mm x 151mm. The 151 mm height is less than the Vetus 158 mm so it should fit. The
Vetus PM111 rectangular porthole has a height of 144 mm so it should fit.
I used the
Beckson PO310, which have an overall height of 140 mm. However they're plastic and the installation isn't too smooth and you have to paint them afterwards. However, they're cheap, open and the ones on Journey On don't leak.
And measure to see what fits. Remember the v-berth cabin has an inside radius at the top and an outside radius at the bottom. I only got the final measurements after I was committed and drilled a hole through the side of the wall. Filling that hole, as the installation instructions pointed out, was easier than filling in the whole cutout if you screwed up.
So, there are a couple of choices. Again, contact Roger on C-Hawk to find out what he used. I just did a catalog search, he actually installed portholes in a 22.
More than you wanted to know?
boris