I understand the "flexibility" desire, but have you ever gone camping with no tools but one swiss army knife compared to bringing a hatchet, some pliers, nail clippers, etc? The "flexible" option can work but it's not well suited to anything because it is OK at multiple things.
In central Europe, this sort of combination pretty much dominates the 40T market; a removeable ~24' container with legs that fold down, and guard rails on the bottom (like a rolloff dumpster). The straight-truck unit drops it's airbags to get under, then connects the claps on each corner, and the chassis trailer slides under the unit along the rails, and connects the same way. You see literally dozens of these containers standing on their own legs at distribution facilities in France and Germany, waiting for a truck to pick them up. Takes all of 5 minutes to load them on.
I’d do it the same way a roll off dumpster is handled . no reason you can’t switch out the dumpster with sides for a dumpster that’s a flatbed . All the hydraulic stuff is gonna add a lot of weight though .