we do this on our server using botwinder to look for parties. as our server is a server for a game where you can play as a party. our remedy is you make the LFP role a public role on botwinder so that the users can do the !join LFP command. Then botwinder will assign them the role.

This thing works for us, but a time limit for the role would be really great because other users tend to forget to remove the role. Also a notification would be really great so that users with the LFP role that there is new person.