We have not rented a power wheelchair, but did check into it last year for DD, from Care. We finally decided not to because of a number of factors (including that she uses a specialized seating system and they could only provide a standard seat).
Because a power wheelchair is a little harder to drive than an
ecv, they will only rent one from someone who has already been driving one. That won't be a problem for your DH.
What they needed from us to set up the power wheelchair was some data from our DME company including measurements. They also needed the settings from DD's wheelchair controller. There are a lot of variables that are set, including top speed in different settings, how quickly it stops, goes to top speed from slow, speed of turning - there are 14 variables in her program and she can have up to 5 programs. The programming of the wheelchair doesn't take them long, but they might want someone to be there for the power wheelchair delivery to make sure everything is set right. On an ecv, there are not a lot of physical things that can change, but a power wheelchair usually has things like height of the armrests and footrests and even angles of things like that which need to be set for the user.
If Care can't help you out, you might want to ask for a recommendation from your DME company. Ours doesn't have a branch in Orlando, but did suggest another company to try that does.
Good luck and let us know how things went.