I've never installed bulkheads before joining the hull and deck, because:
I don't use sheer clamps unless I absolutely need to, and I can't do a decent job of taping the inside seam if there are bulkheads in the way. A good seam tape job is stronger than a small cross-section, long grain, sheer clamp, too. For a boat with a sharp 'corner' at the hull-deck join, a sheer clamp is a better idea, since it's very tough to get seam tape into a corner.

Sure, everything's a trade-off, and I'm not making any sort of "recommendation," just describing what I've decided to do. For me, I'm not confident that my hull and deck are exactly right, so I'd prefer to use a "known correct" bulkhead shape as a reference, and then do any adjustments that are needed to the deck to ensure that it complies with that shape as closely as possible. Haven't fully decided on sheer clamps yet - my initial thought is to install sheer clamps in the fore and aft compartments (bulkheads to ends) and then use seam tape for cockpit area between the bulkheads. Once the deck's installed and the hatches are cut out giving me access to those compartments, I might go ahead and reinforce the joints with some fiberglass on the interior as well. I realize I'll be adding some excess weight, but minimizing weight isn't my first priority.

At this point I just want to get the boat finished in the simplest way possible.