I used a "Danuu SUP leash" and the "Stainless steel webbing eye" from CLC.

It is not really an eye, but has a wide flat opening that you can attached the velcro webbed end of the leash to.

I screwed to the "transom" of the Kaholo and followed Drill, Fill, Drill to make sure the attachemnet was watertight.

David

I just installed a leash plug anchor which I purchased from green light surf supply for $2.50.  it was very quick and simple to install.  Website as follows:

http://greenlightsurfsupply.com/leash-plugs-and-vents.aspx

Mike 

Before decking I added a small block top center of transom. I mounted a small web loop there with 2 oval head screws w/finish washers. For the leash I used 3/16" braided nylon line, a velco ankle sytrap, and a few feet of 5mm bungee. About every 12" I stitched the nylon to the bungee which was stretched out. On the Kaholo the bungee collects the leash aft in a snakey pattern and effectively shortens the leash. Cheap rig but it works.   

I used a Gortex vented leash plug from Greenlight.  It has a shoulder on the lower end, so needs to be installed before the deck is glued on.  I made pregressively smaller disks of 3mm scrap till the thickness was right to make the plug flush with the deck.  My largest disk is maybe 3.5".  Glue deck on and glass over, then sand back till the plug is open.

I used the unvented leash plug but same design as the vented one. I put a small 3/4 inch block behind where I wanted to install the vent plug. Then after the board was fiberglassed I drilled out a hole the size and depth of the plug / flange and dropped the plug in. I then poured in some epoxy mixed with silica into the gap around the edges to secure it. Simple to install and looks great.  I used the silica as much for Color as for strength as as the 1/8th inch circle around the plug will show when it is sanded down.  You could also use some filletting sawdust to create a better color match.  

Mike