Super, it is possible. Ucwepn and I have proved it. The side rods won't break if designed correctly. And chances are Tomy/plarail does not want to make this as a lot of effort would need to be put in the design on the side rods to have them perfected. And with the solid side rod design, the train doesn't seem to like curves much.
Proud owner of Tomy/Plarail trains.