I have been watching Ingrid Klimke's 3 part Dressage clinic using cavaletti. The 2nd episode ("Dressage Clinic", RFD.tv) has some very good ideas that I think could help you. Dressage Symposium - Performance Through Fitness: Part 2 | LocateTV
Using transitions between gaits and the poles at a 1/2-circle will cause your horse to use her hq's without stressing the front legs. If you don't know, Ingrid's father is Reiner Klimke, who authored, Cavaletti
several decades ago. I've studied it, cover to cover. Brilliant.