I found if you use the connector object on a single object you can restrict it to motion on a plane and it will apply its constraints as part of the simulation. However once you dump that object into a cloner, it no longer works. bummer there.
Vid2k2, i ended up doing something similar to your guides idea. I used a wind force to push everything against a vertical plane as they fall. its a hack but it ended up working about as i wanted. occasionally an object pops out in front but its a useable workaround.
Id still love to know if this can be done correctly if anyone has a pointer. The connector object is close, if there was a way to get it to work on multiple clones. Ive also tried PSR constraint (set to generators), but again, once dynamics are active the constraint no longer functions