but its not cumbersome.. towing a trailer .. they use an air hose quick disconnect for the hitch secure and solid.

Bring your gear in a duffle bag , & pack it into the suitcase when you take the bike out and you just have 2 pieces,

not 4 panniers + bar bag + bike. to deal with on public transport , where you have to carry all those bags separately. that Is unwieldy ..


I have seen Bromptonauts making their own hard case towing trailer kits.. ( you tube)


there is also the newer Bike Friday PacIt, it uses the same 349-16"wheel size as Brompton..

but can use a belt drive IGH, or your derailleur drive, It comes apart and folds in combination , and as a result is pretty light.
optional is a backpack..



....