Yepp... This is the most up to date solution, but as separate items both the new train motor and PF2 box will be hard to find even in the secondary market.
If you don't want to change those old gems' nostalgic shape, a battery + receiver box car is the solution. Not the easiest and cheapest solution, but it works.
r_m
If we have a receiver incorporated in the battery box, why do we need any other electric equipment i.e. switch button? Less PF components mean greater MOC building possibilities.
I think the telescopic armed crane is supposed to be in the middle of the two cargo wagons so that it can load and unload (i.e. reach) both. This might be the reason for the length of those wagons.
I Think I Will convert the Green Loco to the preliminary one. Almost all the neccessary parts are included or easily accessibe. It might be less rigid As the official one, but for me more attractive.