Hello !
After some weeks of use, I’ve got some ideas about the proxy exporter that make sens for me, maybe you too ? 
- Auto rename Object when exporting (instead of only yes/no about overwritting)
- A path selector that retain previous used path (as 3dsmax do in a drop menu ?)
- Maybe a favorite menu to retain prefered folders of exportation (cf previous point)
- Auto rename material ? (
- An option to save selected new exported proxies into a new 3DSmax file (I work like this, to just have to merge a .max file into a scene, containing collection of proxies).
My 2 cents !