Here is one of the trailers designed "at home" and built mostly in my back yard shop. I say "mostly" because when I decided to build this trailer it was to be 34' long so I built a pad, fence, door and tensioned fabric cover over a 20 x 55 spot between my shop and back alley. The doorway was sized and placed to JUST be able to maneuver a 34' x 8'6" trailer out through that opening (on jacks, dollies, etc.) but after I finished the workspace our list of "needs" turned it into a 36' trailer that I wouldn't be able to get out the door, so I built it in 3 sections and moved them into a friend's shop to do final assembly. At the rear is an 80KW 600V genset over 1500 litre fuel tank in the trailer. As "6 drum" cargo deck at back doors, a 4600 lb. processing plant ahead of axles, storage on curb side above hose reels, a workbench/1,100 litre storage tank opposite wall, large vacuum pump and booster on wheeled cage between and a 6,000 litre "working tank" over the 5th wheel. All structure, tanks, shelves, etc, built in aluminum and a network of piping connecting the processor, tanks, oil and vacuum systems. Gross is 26k. Started pulling with my little Iveco cabover and that worked fine on the prairies, but sucked the big one once we started going long distances and into the Rockies - so I bought a 450 that pulled and stopped it very well - but was just not cost effective (unreliable) so spent the next 20 years behind my FLD120 (that could also pull our regular semis, so WAY more cost effective than 2 trucks).