: Just an idea

: Has anyone ever considered using bicycle pedals or modified (possibly
: smaller) pedals for a footrest?

There are two problems with this idea. You've hit on the first one:

: The big thing is to make sure they are corrosion resistant for saltwater.

The other problem is the bearings. Most bike pedals will resist a reasonable amount of splashing, but none are really designed for frequent or constant immersion. None that I'm aware of are designed to withstand salt water. Even the best of them will rust and/or have the bearings seize in short order. Consider also that you would probably want platform pedals for use in a kayak. Most of these are not well constructed at all and probably wouldn't last more than a week or two in a boat. Additionally, most platform pedals are heavy compared to typical kayak footpegs.

There's a simple modification you can do to most footpegs to make them more comfortable. On one of my boats, I cut wedges out of 2"x3" material, sealed them with urethane varnish and bolted them to the foot pedals. I used a 15 degree angle, which may be a bit steep for some people; 10-12 degrees might be better. I attached them with a single bolt in the center, so I could rotate them outward at the toe end. This allows me to sit with my feet splayed normally and angled forward. This, combined with the increased surface area to push against, makes a huge difference in comfort. A strip of rubber non-skid tape completes the package. Simple, dirt cheap and effective.