What is the best source for the coils? Kellyco doesn't sell them, right?
I would go with waterproof connectors and get the Tornado 8" DD for working the first drop off and trashy areas.
And the 10X12 SEF, if you can get it.
At the time I looked into it, about 18 months ago, you could only get the SEF coils from Kellyco.
I had a 10X12 SEF coil on back order, which was cancelled when the Sovereign went out of production (sigh)!
You should not have any trouble getting the larger SEFs as Kellyco, had several in stock.
If you go the waterproof connector route, you will need to also change the connector at each coil to a waterproof one as the sovereign is not water proof.
I havn't played with it, but it should be easier to pinpoint with the larger SEF butterfly coils than the circular DD WOT coil.
Also, I have heard (most likely from OBN) that it is more difficult to use the SEF with a waterproof connector and the diameter of the cable is a little wider, and the wires are not color coded