Teacher Discussion Forums

I've been asked to submit a proposal for a very open ended/tentative volunteer assignment (no worries about enslavement - it's a good org I happen to be connected to - and I wouldn't be in it for money/etc.) I'm a fairly experienced ESL teacher with a TEFL cert and maturity. I need to develop proposal to show the org exec for teaching basic English communication to a group of nature guides (in country) - average education probably 5 to 6 years. I've been doing some thinking and research and have some ideas - but need to make some projections on how much can be taught in x amount of time. What's a reasonable amount of class time per day - for how many weeks etc. That's what seems most difficult to propose. . . Anyone proposed/developed any ESP courses that can offer some tips/direction?