Yes, IMHO looking at the Santana version of the Spinergy wheels is a first stop, must have. Previously we had a Team AL with the Shimano Sweet-16 wheels, but these Spinergy have a much plusher ride and much lighter. The cost isn't bad either. Check with Ric at House of Tandems (in TX), Mel at Tandems East, or of course Santana.

The Santa V-fork is not the lightest they offered. We had the Reynolds Ouzo Pro carbon, which at the time was a fair bit lighter than the Santana. I thought the Ouzo ride performance was great, but note it is only for the caliper brake type so you'd need to grab a road front brake.

Interesting to see my BASTARD solution (spring over wire) again Your BB7 rear caliper should be fine with your road shifters, but the Santa cable routing under the bottom tube then up and around the chainstay does tend to cause the cable to bind a little. A good set of cables (casing and wire) can help. I like the Jagwire Racer kits with the solid casings (not weaved) and replace the rear brake wire with their super slick (non-teflon coated) stainless 3000mm (cheap on Amazon).

Very likely with the Spinergy wheels your stoker won't miss the suspension post... saving yet another pound. Santana uses bigger diameter posts, so you'll need to shim a standard 27.2 if you go that route. No big deal and the selection of lighter standard posts is obviously better.