I’ve seen some “tips” on making paddle leashes, usually from barrel connectors and phone handset cord.
I took a cable tie and small carbiner which you can pick up at any Wally world and secured it around the paddle shaft. I then used a small retractable dog leash with a larger carbiner clipped to it and clipped that straight to the loop in the rear seat adjustment strap. The larger carbiner fits fine with no compression or interference with the strap or fit. Then simply pull out the line with the snap already attached to the dog leash from the manufacturer, snap it to the small carbiner on the paddle shaft and you are ready to go.
Works great with paddle clips as the line will retract out of the way when stored in the clip, accessible again when needed and you can even set the length you want with the lock if desired. If you need to unusually reach with the paddle for any reason, just take off the break and you’ve got more line. (up to 13’ on the one I got)
You can experiment with placement as needed if the location doesn’t work for you for any reason.
It just keep a neater and less cluttered “deck” to me. Less “line” to be fouled when trying to play the “big one” and you could just dropthe a paddle overboard if you needed to without fear of current, tide, or wind taking it too far away.
Cost is nominal, about$1.50 for two of the small carbiner, $1.50 ea. for the larger, and about $2.00 for the small retractable dog leash from any supermarker pet supply. Cable ties can be bought for about $3.00 for a bag of them. Total cost for one leash is less than $5.00.
You can even color match the carbiners and the cable ties to the yak color and the paddle shaft. I HAD TO for my wife’s boat(he said sheepishly).
Man, I paid $11 for a 2 oz version from Paddlers Hideaway. Feels like cheating! 
Tidewater 196DC
Yamaha F115
Pungo 120