One solution to the various issues that face the Engineer of Items of Transport upon the Grid - though these issues I believe to be slowly but surely disappearing, hopefully to be banished into the annals of history, only to be brought out again to scare the newest of new residents, "the Sim Crossing Monster will eat you up and spit you out at 0,0,0 with your shoes in your rear end!" - is of course to design vehicles which are purely attachments.
These are sturdy, reliable things, and much can be done with them.