Nowadays I just press the bridge itself with my palm... but it's pretty hard to do a divebomb without the arm.
Here's a little scheme I have: weld some kind of weird flange/flap/wing onto the bridge that's always there... solid... one near the volume knob for divebombs and another on the opposite side for raising. Easy to grab... and yanks like a mo'fo. I wonder if that's ever been done? Would it foul up the intonation or something?
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Also, I notice on the SRV signature Strat, he had a left-handed tremolo (on a right-handed guitar) so that the arm was on the opposite side of the bridge where it would normally be. This meant that he would depress it to do divebombs and yank it up to raise. And it was up top... I think it would have rested on the bridge instead of flopping around like a hanging dang-a-lang, and was less of a reach when he went to grab for it.
That doesn't seem like a bad idea.