Yeah, I was thinking midboom sheeting. Some of the later versions of the boat in questions do have this with the traveler mounted on the bridge deck. I guess I could find out if thier booms are bigger.
I am still not sure how this one would be rigged with only one end to pull on in this arrangement to get the boom to flop back and forth when tacking.
On many non-racing boats, the mainsheet isn't double-ended and will only have a camcleat on ONE side.
On a boat with a transom hung rudder and tiller, you generally can't have a traveler for the mainsheet, since any mainsheet with a single attachment point that is end-boom attached would interfere with your ability to steer with the tiller. If you modified the boat to mid-boom sheeting, which usually requires beefing up the boom to handle the loads or it will snap, you could probably mount a traveler on the bridgedeck or cabintop.