Typically the sissybar is mounted to the rear fender strut.
There's not a lot of room for this with a passenger since the fender strut in person actually extends less towards the back of the fender than it appears in the pictures.
The sissybar doesn't have to look great, mainly to hold a bag for transportation and I feel like I can bend some soft metal tubing into shape, the question is what type of hardware can be obtained to secure it to the frame.
Note that there is maybe only an inch or so here and there of available room on the frame but the sissybar, in my case wouldn't be carrying any more weight that a light bag of stuff.
Has anyone made one with not too great an effort?