Fast opto-isolation with open collector output without VCC
Unfortunately physics dictates a tradeoff with CTR and speed

If you can't make it with this. Change the requirements.

Top signal diode charges up C to become Vcc and  biases the internal photodiode to the external bus voltage peak to store voltage for low duty cycle communication on the bus.

I assumed 5V 300 ohm termination and 100 ohm drive impedance. Change to optmize as required.

Compute worst case CTR, factor some aging of emitter diode and include worst case temperature to ensure high SNR for signal on the bus.

2nd diode and current source generator simulates the opto emitter diode not shown.

Phototransistor can drive impedance of your choice. 



Sim link