Even highly experienced paddlers differ in their views on rudders. Without getting it the pros and cons, here's some thoughts on gas peddles.

Foot room: Most kayaks have amble if you already use footrests for bracing. Your feet should be at a slight and comfortable angle anyway.

Control: Much more then the sliding footrest system. You can brace with one or both feet using a "gas peddle" system.

Force: The ball of your foot is used rather then just your toes. Just tip your foot forward. Minimal force is used.

Length: Set up the gas peddles the same as you would any other footrest. Easy and comfortable.

For a home made system take a look at the link below.

Cheers
GrantG