Those two piece collars are good suggestions. Back when Jay (previous owner of RI) would sell a new snap ring axle and sprocket, it was shipped assembled with the snap rings and spacers in place. It sounds like the guy shipping parts from Mudd Ox/RI is unfamiliar with the process and is just shipping the individual parts by part number only. I recently ordered T20 seal kits and the center gaskets were not included like they should be (they mailed them promptly when I told them parts were missing). Unfortunately in your case, tennesseemudbug, you didn't know what parts you should have received and therefore assembled it incorrectly. I thought about going to the new Max factory and volunteering my time to help them get accustomed to the disorganized parts process that RI has used for years. But, they are in northern Indiana and not southern Florida, so it sounds like less of a good idea at this time of year... haha.
Everybody dies, but not everybody lives.