Pistol lanyards?

[Mr. 16 gauge]

I have a Ruger Mk II pistol that I would like to use on the trap line next year. I will be checking my traps while duck hunting, so water (sometimes DEEP water) is involved, and I will be working out of a small boat/canoe. I would like to put some type of lanyard on the pistol to help secure it....there is no 'ring' or loop like on some military models. Any suggestion as to how to secure the lanyard to the pistol? Anyone have any idea as to how long pistol lanyards usually are?
Thanks in advance........