Plus, the 3/8 were about $2-$3 cheaper per clip than the 7/16...

Well I took a 3/8 over to the rods in the store and they barely fit.. so I went to Home Depot and found 7/16 but they were out of them!!! BUT as I was walking out I saw a shopping cart with a bunch of assorted random stuff and there was 1 in there!! How lucky is that... but it seems like it is going to be perfect.. I am gonna try it out tomorrow probably.

Well I just made mine and it turned out awesome!!! I havent mounted it on the boat yet but I will later..

Ed (BeeReady)also has a round rail mount he sells separately that would work well for your "spring clip" mounting. It clamshells the round rail much like the one above, but just has a 1/4-20 hole tapped into the top of it. You could probably just mount your spring clip into the mount as you see with the square mount.
I use them to mount video cameras, electronics and even rod holders on my kayaks. they have a round grab rail on the sides that I used these on. If I remember right they were about $10 for a set of 2 clamps.
That would be $5 per mount.

You can also buy stainless "U" clamps at Home depot that would do the same thing. They have them in several sizes up to 1-1/2" diameter and they come with stainless cross bar and nuts.

Best of luck, Phill

That is exactly what I got... but I got it at home depot for $1

(The clamshell thing with a 1/4 tapped into the top.)

Works awesome! I will be making 9 more tomorrow.