Shuttle means different things to different people, from someone who meets you at the end of the day with camping gear to a one time movement back to your vehicle. When we did the through paddle, my paddler buddy's wife did the delivery but my best solution for you is to leave your vehicle in Canaan, VT and enjoy the river. There's an Enterprise car rental in Old Saybrook that you could take back to Canaan, returning to Old Saybrook with two vehicles. As you drive north you'll be impressed how fast you cover ground that took you about two weeks to traverse south.
Without outside support at the numerous portages, we became big believers in 'every ounce counts'. Using large fishnet bags that could be slung over the shoulders and a home made yoke each portage required two trips, one person carried their kayak while the other carried their gear taken out of the kayak (and opposite on second trip). Resupply options were limited, especially up north. Having water filtration avoided extra weight of carrying water.
But it is all part of the adventure and you will make some great memories. I was surprised how empty the northern end of the river was (partly due to the river's tendency to flood keeping houses well back) and how much wildlife could be seen. More information available at https://www.ctriver.org/connecticut-river-kayak-adventure/ Good luck!