Building a new smoker, need advice!

Hey all, I'm finally getting around to getting a new smoker built! We've been using one we had built 11 years ago for a Carolina style pig roast for our wedding. I've been running a BBQ catering business for the past 4 years, and food truck for the past 2. We do a lot of fairs, fests weddings, and I have a few spots where we set up all day to vend. As much as I love my old smoker, its just not making the cut anymore... I want something i can use to smoke onsite for as many as 400 to as few as 40, ribs, chicken, pork butts, brisket and the likes. I'm unsure what direction to go in for a new smoker, I want a large capacity, wood smoker, that's mounted on a trailer. I've always loved the idea of a carousel smoker, but don't know if its the best bet. Is reverse flow the way to go? Any advice, pix., plans, and tips will be greatly appreciated!
Thanks in advance!

What I'd like is a large carousel style smoker. I've used a few different smokers and I do know what I don't like. I'm not a fan of a smoke box on the back of the smoker, like southern Yankees smokers, I do like a smoke box further away form the meat, more of a gravity feed system. I'd like a smoker grill combo and a holding box, but they aren't a must have. But mostly I'd like to know what everyone likes and why and what they don't like and why. I've been looking at so many plans, and smokers, I'm overwhelmed at this point. My budget will sort of be determined by what I decide to go with. We have a friend who's a master welder, fabricator who's going to be building it for us. I'd like to give him some kind of a plan we can tweak to fit our needs.