I can suggest to use one of the Primesep columns in which ion-pairing regent is attached to the surface of the silica. Your profile will change but you can find conditions/Primesep column which will mimic your separation with RP/IP combination. See the following link fro "Retention of Polar Compounds without IP Reagents":
http://www.sielc.com/pdf/SIELC_June_2004.pdf
Browse through our methods may be you will find something similar. Look at similar functional groups (amine, amidine, aromatic amines, organic acids, etc.). The principal is the same you retain and separate compounds based on two mechanism: reverse phase and ion-exchange:
http://www.sielc.com/Applications_By_Compound.html
Also you can send me list of your compounds and we will develop method for you (free of charge).
Vlad