I wouldn't do anything much more than the USAA loan (25k, ~$450 a month). Right now that is the only debt I have and its easy to manage. I still manage to save close to entire paycheck a month and its only going to go up now that I make BAH.
I am heavily looking into an 06 C6 Z06, which is probably going to set me back $45k before taxes. But I can afford it, I did some smart investing and by the time I am all said and done my only debt will still be the very manageable USAA loan.
So basically...unless you have another 20-25k in your back pocket AND the USAA loan, don't blow it on a 48k vehicle.