Any good ideas on a good combination throw for SodeTsurikomi Goshi against a stiff opponent?

Short of just breaking the lapel grip first, try this- if they are upright, try kouchi gari, then pressing up under the elbow to break the grip attack the opposite side with the tsurikoni goshi. If they are in a defensive croching posture, attack with a normal tsurikomi goshi first, then breaking the arm grip with the lift under the elbow throw the sode version to the other side.

Nice tip CWP, always try and break your opponent up with ashi waza prior to launching a big hip throw like tsurikomi, kouchi, ouchi and deashi/kosoto are great to set people up for this type of scoring technique, particularly if your work rate is slightly higher than your opponent or they are feeling the pressure half way through a randori session or shiai. Dominate the gripping whilst making the ashiwaza attacks, they are probably stiff arming you in order to get a rest, so keep up the pressure!

Good luck with these combos, practice them as drills on the move first with little resistence then wirh 30% and eventually build them in to your attacking patterns during randori

Geoff