Any other suggestions??

Dave,
I use stainless steel u-bolts and attach hardware under deck with a power ratchet on a long handle with the boat upside down. The first attempt was a struggle but after many boats, I have gotten pretty good at it. This way the u-bolt can be used to lock up the boat. I found that when I embedded hardware, sometimes however rarely, it broke loose if tightened down too much. I also wanted the bolt for locking up and if screwed from the outside anyone could undo it. It can still be taken off for varnishing, since it is easier to varnish a clear deck than around hardware.