Other Car Rental Programs/Partners (ie. Alamo, Enterprise, Sixt) - Alamo MIA - Mustang Convertible? "Downgrade" to SUV?

Hi,

I just returned from LAX and LAS where Alamo had Mustang convertibles in both lots (unfortunately I booked a midsize SUV).

Now I am going to go to MIA and am unsure whether to book a convertible or midsize SUV?

I am only going to be there for the weekend (FRI-SUN) and would really like to drive a Mustang. I don't care for Sebrings at all and am concerned if the weather is not going to be what I expect, whether I'd prefer a midsize SUV (Ford Escape) again.

So three questions:
- Does Alamo have (any / plenty) Mustang convertibles in MIA?
- Would those usually be equipped with Sirius/XM (all Ford Escapes had it)?
- Would I be able to "downgrade" from convertible to Midsize SUV if I arrive and won't be able to find a Mustang or will have changed my mind by then?

Prebooking from Germany the price is identical for Standard SUV and Convertible, while Midsize SUV is cheaper. I therefore assume it would be safer / easier to book a Convertible and downgrade, instead of upgrading from a Midsize SUV.

Anyone?

I guess the key question is:
Could I book a convertible and leave the lot with a SUV?

Can't make up my mind and really should book by today. I would expect it's no problem since the convertible is more expensive.

If it is, I may need to book SUV instead.

Thanks