We gave it a go
After a little while something felt not quite right, the back tyre was soft, an odd feeling on a tandem. So in the blazing heat I changed it out.
After the turn around spot, we kept our eyes peeled, it wasn't hard to find in the middle of the trail a mile back or so.
We managed one more hill climb, but on the decent the spare tube also gave out, I tried the first tube again to try and limp back, but it was flat in less time than it took to inflate. It was a hot short ride but fun anyway, even if we had more flats than miles. Ended with a refreshing dip in the lake.