@chiefan, I am sorry to hear about the accident and the frustration you're having with the rental reimbursement coverage. I asked a business specialist to research your situation further and to follow up with you as soon as possible. Thanks ~ Robert.
Rental reimbursement is on a dollar basis not a size of the vehicle basis. Generally you'll get $30/day for 30 days with a limit of $900 per claim (or something like that policies vary and you can choose the amount).
However the Texas Department of Insurance is a great agency and they can answer questions for you and take a complaint as well. Insurance companies take their state regulators inquiries very, very seriously.
That said it may be the rental car company giving you the short end of the stick. You don't have to use the one USAA recomments (Enterprise I think, I don't care for enterprise). Call around and ask for a good rate. Many companies will direct bill the insurance company, but if they don't you can pay and get reimbursed up to your policy limit (the 30/day $900 per claim or whatever yours is).
@chiefan, I show that on Friday afternoon, Robert escalated your situation to the CEO Member Relations department to review further. They will be reaching out to you within 2-3 business days to discuss your concerns. Thank you.