How about making a 6ft lifting pole to hook into your stern loop? A greenland paddle would work nicely with a 'pouch' slid over the end to secure a rope.

Sit the nose of the kayak on your loading wheels on the windowsill, lift the tail up with your pole, and slide it on in the window while standing outside..

That might be the simplest solution? Just make sure there's nothing expensive or fragile on the coffee table first as the nose is going to drop once you get past halfway!

Seems a shame to make the boat heavier than it needs to be for it's intended purpose..