I don't see why not. I rent a car by the month from Enterprise. It costs $691 a month and each month there is an authorization for $700.
$650 available credit is more than enough for two days!
It should be fine. I wouldn't mention it being a secured card, there's no way for them to know it is. Generally enterprise authorizes $300 on a card up front.
I highly doubt they are going to put a hold on your card for over $650, you should be fine!!