You can get padeyes, cord, bungee and stainless screws/washers/nuts at most
marine suppliers. Yakima footrests are available as an aftermarket item. All
attachments will need to be done via drilling holes in the boat and installing
the parts with screws or stainless pop rivets, since you cannot easily glue
anything structural to polyethylene.

Another important concern is floatation. You should install float bags front
and rear. Without them, there is no way you'll be able to self rescue in the
event of a capsize.

--
Regards

Brian