So I went back and switched to the fat bike. I was a bit hungover from a Fossil/Trails End double the night before, and hauling the fattie up Barr Trail through all the Incline folks was quite the death march.
But holy cow it was worth it. The missing link, which is officially known as the Lake Moraine trail, is a fantastic ride. You turn off Barr Trail just before Barr Camp and the trail takes you over to Jones Park. We catch 667 which takes us to Captain Jacks and then it's just a long downhill to Fossil. Such a great loop. There's also the option of shuttling up to Elk Park and dropping down to Barr Camp, thus avoiding the traffic on Barr Trail. Will definitely do this ride again soon.