I did a search and found all kinds of things for lowering, but didn't find anything for increasing towing capacity. I've got a query in with Spring Works, but won't hear back from them for a couple of days. I did see that there's a spring company in Australia that makes overload springs for their version of the Camry, but there's no guarantee that they'd fit a U.S.-built version and no word on cost or shipping time. I've already added a transmission cooler, so I have that taken care of.
Yes, I saw all the "get a truck" comments from other towing threads, but it's $1100 to rent a truck for 1400 miles and buying one is ridiculous for anyone who doesn't need a work truck for a living. People used to tow with sedans all the time with much worse engines, suspension, and brakes, and did it with aplomb, so I'm not worried about longevity as long as I don't exceed the capacity of the hitch. I just need to keep the back end up with 350 pounds sitting on the ball. If need be, I'll get some heavy rubber spring spacers from O'Reilly, but I'd prefer a better solution. Thanks.