The brown guy brought another Aircraft Spruce box today. One of the things in it was the MAC POS-12 flap position sensor. With it, the Vertical Power VPX gives you presets for flaps. Easy enough to install, though it takes a little while to get the rod length and bracket position right.
I'm thinking I don't have a problem with the rear seat belt mount...but I'll concede that I'm not certain. Spruce doesn't carry the rod and clevis for the POS12....so I had to get them from Amazon. Du-Bro 817 kwik link and 379 rods.