Question about upper and lower boom caps and sealing


I installed new top and bottom caps on the mast yesterday. The bottom cap was missing on the Sunfish I bought.

Now I want to replace a cap on the lower and upper boom that are damaged. When doing this do you try to seal the booms like you do the mast plugs? I sealed up the mast well, but I am unsure if I am to try to seal the lower boom. It would seem to be a futile effort given the through bolt on the front of the lower and upper boom to tie them together. What do you guys do?
Ive done two masts so far with the following procedure:

When the time comes to replace spar plugs, I'll spray a product made by "Great Stuff" called Pond & Stone inside both spars. At $8, it's a little pricey, but weighs nothing at all and could save a long and difficult recovery righting after misadventure.

I suspect filling needs to be strongly sealed at the filling end to force the foam as far as it can go. Once used, the spray left in the can won't be serviceable for very long, so line up your projects, or make a huge block of dark gray foam for a sculpture project.