Is it possible to transport many (up to 12) bikes using some sort of auto-trailer? I would like to be able to use a trailer, either open-air or enclosed to transport multiple bicycles at the same time.  When I google hitch racks the maximum is 5...I am looking for a towable option...do these exist? Where can I find one?  Could I make one?
Where I live it is common for commercial operator to purpose build trailers for carrying bikes such as these. 

The other option I have seen is custom bike racks for back of any flatdeck trailer or trucks.

One event here has over 1000 entrants to a relay - they need to transport 1500 bikes on the day, up to 100km..... So it's certainly doable.... I am glad I don't do their logistics planning...