Tony, I've only done three s&g kayaks with interior deck/hull seams and 6 CLC constructions with spread sheer clamps. I found the task of putting in an internal seam perfectily doable given the rewards in the end product. I could imagine sheer clamps on finished hulls where the sheer clamp is not a part of the hull shape could be a little easier but everything seems to be some kind of compromise.
On long boats you can work through the cockpit and hatches. It's not necessary to do the whole interior at once. I never used a piece of tape that was longer than the one in the cockpit. The whole process a lot easier in the ends by pouring a couple oz. of slightly thickened epoxy down the interior seam while the hull was on edge and tilted slightly. That gave a little fillet to rest the tape on and a small endpour that was angled according to the seams. All of the "it's so hard reaching in there" isn't offset by the compromises in hull shape that a spread sheerclamp construction brings,,or at least an untested hull shape.