Daleyellin, unfortunately, the 192/222 just doesn't seem amenable to a traveller. I have thought about where I could put one myself. The easiest would be the aft edge of the bridge deck, but the bridge deck is far to narrow to get any decent movement. You wouldn't be able to move the car far enough to windward to get the boom on the centerline.
I thought about putting a track on the aft coaming lip, but then I remembered the tiller comes across the transom. So, then you'd be building a raised bridge in order to clear the tiller, and that might get clunky. Perhaps something made of custom welded SS square tubing would be strong enough and low profile enough to mount the traveller track?
Then, based on your description of the cabin top, I wondered if you meant to make a raised bridgework to go over top of the sliding hatch lid. But there are issues of where to mount to the side of the cabin top, and then once it's there, you've got an obstruction to the companionway opening. Even if it was forward of the aft edge of the cabin, it's still right over the top of the opening when the hatch is slid forward and open, and I stand up in that area all the time. So that's a non-starter for me.
So for now, I have just resigned myself to having the end boom sheeting. It's all a trade-off; either I have a boat with mid-boom sheeting and a traveller across the cockpit seats and better performance, or I have a comfy large cockpit. Since the boat is purely a cruiser, and nowhere near a racer/cruiser, I'm fine with her as she is.
Further to this, with my rig loaded to roughly 15% of the 1/8" wire breaking strength, I think my rigging is a little tight, as I seem to have a fair amount of mast pre-bend, and keeping a reasonably tight backstay, I feel I've got a bit too much tweak at the top of the mast. I'm afraid if I tried to make the backstay adjustable, it would induce too much tip bend above the hounds... I'm very happy with the rig balance now, and I'm loathe to pull all the dang cotter pins AGAIN to loosen the rig some more, so I'm keeping her as is for now. I tried to tighten the lowers and pull some of that pre-bend out of the mast, but now I'm worried because the rigging instructions say the lowers shouldn't be tight at all. Yeah, I think I've got the rig too tight. But I hate jib luff sag!
Brian