Not as difficult or time consuming as you may think -- it's all repetitive cuts, rafters, walls, etc. both sides are the same as are the ends with the exception of the opening.
If you want it to last, you really need to build a 'wall' 2x3's work good -- 100 people, let's say you get 5 good work hours of of them, that's 500 man hours, divided by 50 dog house, gives you 10 man hours build time for each dog house -- I think you can do much more than a plywood box screwed together with that amount of manpower.