When I was still co-owner of an RV-4, we've discussed the open cockpit option. We figured that an attractive way would be to build a side-hinged canopy that would have the windscreen, would close off the rear cockpit and would replace it with a raised turtle deck/ headrest, and would wrap around the pilot rather closely to avoid too much draft and buffeting. The fact that it would be side-hinged would make entry and egress a lot easier, plus converting it between two-pit closed bubble and single-seat open-top would be as simple as pulling the piano hinge wire and swapping out the canopies.
No reason why this wouldn't work on a side-hinged -3.
Mine is a slider. Different game. Plus I already have a Fly Baby to scratch that open-top itch.