It was done in a few VERY, VERY old TV sets (the first Bush A823 series for example) - as in post #12 you need a special driver transformer to feed the transistors (the TV used one primary and two secondaries), it also had balancing adjustments on both transformer base circuits, which you had to adjust when you changed the transistors. If you didn't adjust them accurately, then the new transistors died in a fairly short time.
However, there seems little need for series transistors in the OP's application - simply use a more suitable transformer, rather than trying to drastically exceed it's input voltage limits, which could well make it break down anyway.