Thanks to project SABLE folks who pointed out that our GPS was one that would not work above 60000 feet (oops). We ordered a new Garmin GPS (see parts list) to replace the Byonics GPS. Here is the list we found for GPS receivers that work at >60k ft.
We had another 2 crammed work days: setup up new GPS; soldered the new power connection to a DB-9 connector (for connecting GPS to RF transmitter); bought and setup a 2nd RF scanner; setup a 2nd laptop for 2nd chase vehicle; setup a spreadsheet to do all our math calculations (helium needed, ascent rate, burst altitude); tied ropes to connect parachute to cooler; punched holes through the cooler for the camera lens, antenna, and the GPS receiver; setup styrofoam shipping wedges to hold the camera in place in the cooler; created S- hooks with 90 degree turns to attach the ropes to the threaded rods on the cooler; and we've run a lot of simulations on ballon track with our spreadsheat numbers to decide if we should launch this saturday or not (tomorrow). For now we've scrubbed the launch. I suddenly have a lot more sympathy for why NASA is always moving the shuttle launches.
We've also decided that in hindsight, the parachute is too large. We don't need it to land like a feather - we just need the cooler and camera to survive. Our current payload estimate is 3lbs and our chute was rated for 3.5-8lbs (R7). We'll try to exchange the chute for a smaller one - maybe something in the 1.5-2.5lb (R3 or R4) range. Thanks to the folks at Rocketman for their advice here.