Occasionally I've had to take two trips to the store 'cause I couldn't carry everything in a single trip. Solution: more carry capacity.
Found a plastic crate in the trash at work, cut a couple of pieces from the bottom so it would slip over the sissybar. Hmmm... a couple of u-bolts, not quite, add a steel bar, perfect. Easy on-off, tighten the u-bolts and it is remarkably solid.
Got to test it out today, went to Top Value, picked up my tea ($1.18 for 100 tagless bags), sugar, a head of cabbage (for rolling) four large bell peppers (for stuffing) and a large cucumber (hey, it was only $.33!). That all went into the saddlebags with room to spare. Then across the street to Smart and Final for a box of wine, and since I was there a sixpack of corned beef hash, a family size box of Triscuits, and an 18-pack of eggs. The eggs got to ride in a saddlebag while everything else went into the box.
I like it!! Worked Perfect!!