What design considerations determine what kind of power supply I should use for a high-side FET?
Yes. Any form of isolated or boost supply can provide the high-side gate voltage referenced to its source. 
Some ideas: 


Floating Charge pump (I was considering the LTC1754 for a very
similar application)
Small flyback with output referenced to source
Floating boost 
Photovoltaic cells powered by on-board LEDs (Photovoltaic Isolator)


The main concern is level-shifting the control signal without killing your deadtime, introducing too much latency, or slowing down turn-on.

Obviously you need to be cautious of exceeding the Vgs during turn on/off of the floating supply also. 

Some references: 

http://www.vishay.com/docs/91421/appnote9.pdf

Is it safe to &quot;top up&quot; bootstrap capacitors using a charge pump?

http://www.ti.com/lit/an/slva444/slva444.pdf

https://www.fairchildsemi.com/application-notes/AN/AN-6076.pdf

http://www.irf.com/technical-info/appnotes/an-937.pdf

http://www.vishay.com/docs/91421/appnote9.pdf