The Allmand 23 (HMS 23)
https://sailboatdata.com/sailboat/allmand-23-hms-23 looks like it is designed for taking on December gales single-handed in the North Sea. Kudos for trying to get it to move in light air. The cutter rig is often seen on on long-haul passage makers because it provides a way to hoist a variety of sails to keep the boat balanced in different wind strengths. If you're making one long tack, the two foresails can help provide more drive and keep the boat steady, especially on a reach, when there will be a bigger 'slot' for the staysail to work in. The cutter rig is not known for being close-winded. In light air and working upwind making multiple tacks, the cutter rig is less desirable. The inner forestay increases windage and the staysail cannot be efficient, working in the narrow slot, backwinded by the larger yankee. The inner forestay makes tacking the bigger sail a real chore. Some owners furl their yankees, tack, and then unfurl it again. Many cutters make their inner forestays removable to avoid this problem. The owners then lose the hyfield levers used to rig them, and stop using the staysail altogether. It would appear that the HMS 23 is rigged as a cutter to permit a singlehander to furl the outer jib with a roller-furler without having to go forward, and to continue sailing with reduced sail area with the staysail keeping the boat balanced. In your light-air scenario, you want maximum sail area, but perhaps not the windage and hassle of the staysail. Make it removable, take off the staysail, and see if opening up the slot and reducing windage doesn't help.