I would like to purchase and/or fabricate a larger luggage rack than the factory chrome one.   Anyone know a source of such a rack or plans to fabricate one?

Someone did that, it was a big, good lookin thing,, I didnt think the square corners on the back were a good idea, but generally, its just time to get some square tubing & build a frame up thatll attach to the bike & lay flat across it. If you can build a sissy bar & attach that securely, you can add a shelf on the back,, Gussets/braces where loads attach. Need a welder, some clean way to cut, chop saw if you can justify it, or a grinder with a cut off disk. Cut off grinders cost a lot more than grinders. I modified a grinder to accept cut off disks. Never use Harbor Freight grinder/cut off disks. The evaporate & sling garbage everywhere. Use the more expensive stuff like from Lowes. DeWalt & others in that range. They last so much longer they actually cost less to use.

It aint gonna be pretty, then,.,& aluminum & rivets wont last long, IMO. Not with any kinda load.