Just don't see the point using TPDT when using limit switches...as you have to control the polarity reversal by limit switches and the polarity modules accept trigger input which is easily accomplished with a limit. There is no purpose to interlock as there is no need to sync relays. Sorry Alan, we also do custom large venue theaters. On wider, heavier accoustical screen curtains we are faced with the exact same issue, only larger motors set up like a slide gate operator using simple limit switches. At UCF learned a unique way for electrical engineers to test a circuit design by having us stand up at a large dry erase board, draw our design in black then apply power in red. Works and gets the techs off the job in the field with stable product.

Hope I didn't offend anyone. Already worked out issues like this post in my career.