"tompn"....I don't know if you'll take the 101 Frwy or I-5 when you leave, but if you take the 101 Frwy, there is a place in Oxnard, just north of Los Angeles. It's called Daniels Tires. It's a Goodyear dealer that does large truck tires and alignment.
They aligned my Monaco twice over a ten year period. The alignment guy is very knowledgeable and they use a 4 wheel laser alignment setup. This ensures that the rear wheels are facing the same direction as the front. Last time I had it done, it was $150.00. They're not so busy that you would need an appointment. Just let them know what tie you'll be in and you can just wait. Half hour to do the job and probably 45 minutes to an hour for your turn.
This way you'll have it done before you arrive and can see how it works on the remaining drive to Indio.
They have several shops and while looking at their website, they have a couple of stores down south, including Indio. I like the Oxnard store because I know the alignment guy is good. They also have stores in Bakersfield.
Oxnard, CA Location information - Daniels Tire Service