Are you able to look at other boats in your marina to observe how they are set up? Doesn't have to be a Hunter 27. Talk to other owners who can help you with ideas while actually looking at your boat.
Just some brainstorming:
Certainly you can lead halyards back to the cockpit and tug on it from there without a winch. But you at least will have to install some cleats to tie the halyard off, or run the lines through clutches, which also would need to be installed.
At 36' loa and an extra 10' of mainsail luff than you, I've got more sail to hoist. Nonetheless, I can pull it all the way up by hand from the cockpit without winch assistance. But I certainly can't tension it enough to avoid scallops in even modest wind. A winch is a must for tensioning. Even with a winch, when the wind pipes up, I get scallops along the lower 3rd of the luff. For this, I tension the cunningham which pulls the lower section of the luff down. My cunningham line is also leads to the cockpit. Its on a 3:1 purchase and I secure with camcleat. I don't need a winch for the cunningham.
As Ed has conveyed, his Cherubini 37 doesn't have an aluminum backing plate built in. Instead the cabin top hardware is secured/backed from underneath. You would have to make a cut-out in your interior liner. Then cover the cut-out with a piece of teak. Or even find some white 1/8" plastic sheet. All this would take time, but its DIY'able.
Next time I'm at my boat I'll take a picture of how my cabin-top halyard winch and clutches are arranged. However its nothing much different than you will see on many boats in your marina.
