We have not done it, but have investigated it since we didn't want to travel with DD's power wheelchair. We didn't do it because DD is sort of an unusual size (very thin, but needing a pretty long seat) and they could not provide a size that would fit her. She also has some positioning needs that they could not provide.
In general, the rental companies will only rent power wheelchairs to people who are already familiar to using them. The probable reasons for this are that power wheelchairs are a bit more difficult to drive than an
ecv if you are not familiar (driving with a joystick is not really intuitive and requires a bit more practice than an ecv), need some individual set up (compared to an ecv, which is more one size fits all) and are a
lot more expensive than an ecv.
The information we were asked to provide were size (length and width) for the seat and some parameters for the computerized drive system (top speed, how quickly it accelerates - I think DD's power chair has about 8 parameters individually set for her that we provided).
I guess I would contact the company you are thinking of using and discuss your needs with them. It's possible that a "general" rule could be bent if an ecv would not work.