Need Ideas

Ok - I have many questions.  I have been smoking for many years on a New Braunfels look-alike.  Now I want a big trailer mount smoker.  LOL.  The local lodge has decreed I am the bbq master, and now they want to sell some ribs for a fundraiser and we are having a bbq dinner in a few weeks.  Awful hard to cook for 400 on such a small smoker - but we have did it before.  Anyway - the only thing I am pretty much decided on is a reverse flow.  I really would like to build a Lang clone, although I saw the build of a bottom fired reverse flow pit on this forum - and thought it looked pretty amazing.  I am unsure how that would scale up to something much bigger though.  I already have some heavy wall 36" pipe donated to the cause (2 sticks at I think 6').  I would love to build something big enough to hold 100 slabs of ribs, but I am thinking 10' long would be about the best size.  Tell me what you guys think - any ideas, or thoughts would be appreciated.  This build will take some time - it's a bunch of volunteers and we are trying to do it on the cheap (all of our money we make goes to scholarships and benefits for others in need), but I do promise pics and updates.