I currently have quick detach brackets and I was wondering if I can piece together a comfy rear end for the old lady, maybe with a small luggage box but mainly a tall-ish back rest with arm rests and a cup holder, not the type of armrests that look like an examination chair but more like a full fairing, any ideas for the 2003 Superglide Sport?

 

Sure you could. Check ebay for a tourpack mount for Dyna. Unless you are good at fabrication/welding or know someone who is.