Lifting was an issue with us, too, for loading both my Shearwater and my wife's Necky onto an Explorer. Ended up with "Hullavators" . Load the boats at waist height on the side of the vehicle, then the unit "assists" lifting it up onto the roof. $$, but it works for us. Good luck

���We use Thule Hulivators too.

���Hullibator deals can be found. Check Amazon, Prime

Rollers on the aft rack and saddles on the front may be another option.  That is how we carry our Shearwater Double (78#) on the truck.  I can load solo by using a cart to position the boat, then lift the bow up onto the rollers with the stern still on the ground.  Then I go down and pick up the stern and push forward onto the truck.  I have a three step stool that allows me go easily up onto the tailgate while lifting.  This is obviously easier when my wife helps.  Picture was launch day so you see foam blocks.  They had too much friction so I bought the rollers and saddles shortly afterwards.

Depending upon the width of your truck rack and boats, you may have a width problem with both boats sitting flat.  The 25" SW Double and a 22" wide Ch17LT just fit on my racks.

   I have a strip of carpet I roll out from the hood of my Jeep up across the windshield to the roof rack. I lift the nose of my Shearwater Sport onto the hood/windshield and then lift from the stern to slide it in place. The carpet helps it slide and protects the kayak and car from scratching each other.