You can tow from near one end of the main beam, inner gunwale side. No need to balance it by a second line on the other side. You can easily control off centerline force on the boat by steering (assuming you've got rudders and center/dagger boards help).

We were towed in two weeks ago from ~8 miles out in the channel after a 6+ hr race round the island when the winds died. We had an I20 in front of us on the tow line. We tied off to his rear beam, left end and I wrapped the end off to our right side main beam end. Worked well.

BTW, I like to wrap, not tie off the line to the boat...just in case you need to release quickly. We hand-hold the loose end...all load is taken by the wraps.