I have two 8' x 32" benches that are normally on either side of my radial arm saw that I simply slid together to make a 16' long table for building an Arctic Tern. Don't make your work table too wide as you need to reach your in-process kayak from both sides.

I only glassed the inside of the butt joints, but I doubled up on the glass thickness to one 6oz about 3" wide, then covered that with another 6oz about 6" wide. I had no problems what so ever with moving the panels around either. Just be carefull and you will be fine.

Don't over think the butt joints as the wood is used as a core in a fully fiber-glassed boat.