I was unaware the tour pak on the FLHTCUSE3 had a detach option? I understood there was just too many electrical hookups for speakers/taillights/Security power, etc.
I'm interested in how you did this and what it cost to do this on your ultra. I was able to do it with no problem with my 04 Road King, but of course that didn't have the speakers, taillights, etc.
We are not talking about a CUSE3, Myself, Boatman and Lets Roll have the CSE2 (2005). Those bikes came with a detachable tourpak with only an antenna and interior light.
My tourpaks (king and chopped) each now have extra lights, 12 volt power supply and in the kingpak speakers.
I made quick disconnect harness using the available from HD, Deutsch connectors. Same connectors that come from the factory.
I am in the process of trying out bulkhead connectors on the tourpak. A problem I now have using a Corbin seat is the rigidity of the seat pan, not allowing the seat to be tweaked in order to hook up the harness.
If you are willing - you could probably do it to your tourpak for under $50, not including the docking hardware. There are others that have done just that on this site. Try a search.