I don't need a full fledged casting deck, just enough room to stand and mount a small pin style seat bracket to. I'd use the seat on the floor when running, then pop it up on the back when needed. Since I stand most of the time, I'd probably just bring an extra pedestal with casting seat and just pull it out when I need to make a run. Essentially it would need to be about the same amount of width as a bench on a small jon boat. I've been looking at the Mercury Big Tiller which would easily accommodate that, in addition to controlled trolling for spring striper. I've found 20' tiller boats for sale in the NW, but nothing nearby. 18' is my goal, but I didn't want anyone to think I was disqualifying something 18'6".
The reason I've been leaning towards welded is mainly because of the warranties and because of the pounding the hull is going to take in the bay. But it's also experience with perfectly dry riveted boats leaking not long after beginning to be used in the bay. It seems like that G3 would be perfectly capable with that double plated hull, but that adds weight to the rig. The only performance bulletin I could find was for the 16'7" with a 50hp on it. That maxed at 30mph with just 6.6 gallons of fuel. The 18' Kodiak w/60hp maxes at 36mph with a full 17 gallons in it. Granted, it's not a huge difference, but occasionally with 3 guys onboard, it may be. I'm just not finding enough feedback about the V177 on the web, which makes me somewhat hesitant to take the plunge on it.
I think I've come to the conclusion that the Kodiak is what I'm going to go with. It offers basically everything I want and I realize that I'm not going to find that Cinderella boat out there. But anyway, thanks for all the input guys!