I think there is a fundamental flaw, because when I tested it, Q1 did not turn on - if 30V was present at Q2's source.

Indeed, the schematic doesn't correspond to what I [badly, I must admit] described: you must exchange the location of R1 and Q1 in the above circuit. R1 should be connected between R2 and Q1, and Q1 should be below R1 and ground. As it is, Q1 can't turn on because the voltage across R1 is too high.

There, with the schematic, it's probably clearer.

Regarding the transistors collector-emitter rating, indeed, you need to take this in consideration. As you say, the transistor will see the full VCC voltage when it is off. Add some safety margin: don't use a 30V-rated transistor with a 30V supply. The supply certainly has some tolerance, so if you're unlucky, the transistor could blow up. Something like a 40V rating would be fine.

@NickGammon [pinging because I'm not sure you'll get notified of my answers by the system]

@dim I realize I drew something different, I was hoping that the moving of the resistors would lower the voltage presented to Q1. So the simpler solution is just to get a different transistor. So you don't have a problem with the 2N3904 which has the maximum rating of 40V?