tmux command-prompt press enter?

Is it possible to include a enter character for tmux to use when using command-prompt’s -I option?

I’d like it to operate like a key-press; but n and r don’t really do the job.

The command argument would maybe include it in the string that I set the prompt with…

Or maybe it’s better to just avoid it all together than just use run-shell, but then there won’t be any command-prompt residue if I want to bring up the old command.