Key binding to swap shell foreground/background jobs

In spite of heavy tmux use and switching between panes, I still frequently find myself using shell job control. When something needs poking I'll background the tool I'm using with Ctrl+Z, poke the thing, then fg the tool again. The issue is sometimes the "poking" turns into using another tool and I want to go back and forth a couple times. Would it be possible to bind another key that is trapped by the shell (i.e. not ever passed though to a foreground app) that backgrounds the current job and foregrounds whatever the most recent background job is?