I'm not sure what you mean by "not having much luck with UShip"? Do you mean they are not providing a quote, or that you don't like the quote?
The way the car transport biz works is that brokers (like UShip) interface with a customer and get the details on the shipment. The shipment is posted on a nationwide electronic bulletin board. Truckers build their route by committing for shipments on this board. Only the desperate truckers are going to commit for a lower than market priced shipment, and the shipment can sit on the board for some time until a desperate trucker comes along.
San Antonio to Indianapolis is 1,200 miles. $1 a loaded mile is a good budget number for an open carrier. You could probably get it done for $1,000 with some patience depending on the time of year, current fuel cost, and the economy in general.
If you are still living in NorCal, driving to San Antonio with your truck, renting a trailer, taking the car to Indy, and driving back to NorCal is not going to pencil.
If you are now living in San Antonio, and are thinking of renting a trailer and taking it to Indy and returning, it still doesn't pencil (gas for 2400 miles @ 15 MPG @$3/gallon=$480, 3 motels @ $125 each=$375, food $30/day for 4 days=$120, trailer rental @ $100/day for 4 days=$400, Total=$1.375). This assumes you have a truck big enough to tow, you don't experience any breakdowns or delays, you don't factor in maintenance and depreciation on the truck, you don't mind driving steady for 4 long days.