What are the advantages and disadvantages of different pedal formats for a recumbent?
You can add "heel slings" as a choice too.  They hold under your foot's heel.

They fit flat pedals and do not provide any cliplike retention.  Instead they are a hammoch for the back of your foot (heel) to rest in.

http://www.bentrideronline.com/?p=5131

These wire ones look uncomfortable, but shoe choice comes into it.  Prolly not good for flipflops or sandales!



http://www.jsrldesignllc.com/  and    https://tadpolerider2.wordpress.com/2017/09/15/jsrl-design-vs-terratrikes-new-heel-slings/

Terratrike sell some that are more strap and less like a garrotte-wire.