If you hunt areas with tidal currents, make sleds not V-Boards. The difference in drag is significant, plus even with a full body in front, the lead leg can have issues staying horizontal against the anchor pull.
IMO, 2x2 is overkill, not needed. You want the arms to barely be above the waters surface, more stable that way.
As other noted, if you have strong currents, sleds might be better.
I have Canada goose v-boards made with 1x2's. I think the arms are 48" long. They float just fine. I thought I would need to add foam, but didn't. Brant shoudn't be any issue.
Harold Hammond made goose v-boards with about 36" of line to be clipped to the back of a goose decoy. He hunted in water about 30' deep and since it would pull the vboards horizontal instead of vertical they would ride great and wouldn't pull under in heavy tides.
I would be hunting the coastal marshes of NJ. The tide isn't that bad where I gun. The ditches have more current than the main bays. ESP in protected coves
I never went crazy on them. White primer roll the edges. As for the arms I've painted them black or gray. I've seen no difference in how the birds handle. For the V boards i've made broadies, buffies, and old squaws. All those birds fly close to the deck... brant included. They will never see the arms.
I used Rustoleum black, white and grey, no sealer. Arms are grey.
I think the plywood I used was 3/8". Never had a problem with delamination.
Sold them all to a couple of guys on here, I bet they are still working just fine.