I was looking on YouTube at a couple of history clips of some American trucking companies and came across the following. Something called Jifflox It lets a tractor unit haul a single 45 or 48 ft trailer as a three axle tractor or 2 28 ft trailers as a two axle tractor with a dolly between the trailers.
https://www.youtube.com/watch?v=oYC9emNN7EU
Something new to me and I thought it may be of interest to share
Always interesting to see different ideas. I know before they went into liquidation Consolidated Freightways had problems with the maximum vehicle length legislation in different states and they came up with some interesting solutions.
In the UK the Foden TwinLoad was one that comes to mind.
If the link doesn't work search YouTube with "Hookup and Drop Procedures 28 ft Doubles"
Doug