Outrigger placement help

[bigeasy1]

I'd eventually like to put some outriggers on my 23 Tsunami,but am not sure of the best mounting location for them.
I only troll for Salmon on the great Lakes,and mostly run planer boards to get the lines out from the boat,however,when it's rough the boards don't perform the way they should,and can actually flip over and act like a diving planer,(not good at all).

From the pictures I've attached,can any of you saltwater guys tell me where the best place to mount them would be.I would like to mount them off the radar arch,but don't know if that would be feasible.
The aluminum mounting plates are (I think)1/8" channel,and are very strong,but not sure if they are sturdy enough.
I also though about the gunwales,but my canvas comes down just past the end of the window.
I run four downriggers and usually one wire rod off each side.

What length riggers would be the best?I was thinking of maybe 18 footers,or even 20's
Also are there any affordable good quality ones on the market?,or would I be better off buying used?
Any info would be appreciated.Thanks guys

THE ARCH BEFORE INSTALL SHOWING THE MOUNTING AREAS.