you mean, can it be done in GPO or can it be done with real basses?
In reality, tremolo can be done with basses very well, but most basses need slightly more time to develop their tone after the bow begins to move. That means the bass players will do their tremolo somewhat slower than the violins. AND the minimal volume is not so low as with violins because they need more pressure on the string.
Let your right arm fall down at the side of your body and then raise the underam until it is horizontal. Make a fist around an imaginary pencil that is vertical. Now shake the whole underarm in quick movements from left to right and back, moving about one inch or 2 cm. This will be about the speed of the bass tremolo. Also you will get a feeling for it to be somewhat exhausting after a while.
The violin tremolo is done with the wrist and the fingers, this is the second reason why it can be faster: it's not only the instrument that is responding easier but also the moving mass is smaller. (Yes, there can be a wrist movement with basses also but this is for illustration of the difference).
So - tremolo is possible with basses very well but it will be more like a bumble-bee than a bee.
In GPO there is a keyswitch in the KS versions for tremolo. Most convincing will it be if you add a little crescendo or decrescendo all the time. Also it would be good to take special care of the beginning of a tremolo - often it will start either with an accent or out of the nothing.
I meant real basses.
Your answer was very satisfying and the technique looked familiar to me. I tried your "faking the movement" and indeed it is hard to maintain. To avoid RSI I stop shaking my right hand/arm now.