Hondaline Backrest Mod Idea/Question

I'm a new owner of a 2006 1800R and I wonder if you all might help me pass a long winter in Michigan by thinking about ways to cheaply (but goodly) putting an armrest for my wife on my standard Hondaline backrest. I like the looks and simplicity of the Graber Enterprises backrest, but I'm wondering if there might be an alternative. Is there any creative option to take a less expensive backrest that has armrests already integrated into it that could possibly be slipped over the Hondaline backrest frame and then resecured with the original screws)? Or, alternatively, are there any designs for sturdy home-built wood-frames to attach to the metal frame (even if they involved self-upholstery?). Might make for a fun wintertime project...