Travel job in SD

Hi everyone, I'm currently looking for a travel assignment in SD and have a job interview tomorrow with American Mobile. I have been an ICU/ED nurse for 4+ years and make plenty of money in SF. However, I'm not in it for the money and that is why I want to move to San Diego (but of course I need to pay my bills). I'm not 100% on my move to SD so I thought I would try a travel assignment. I've heard a lot of bad things about American Mobile, but I went through them because they are a large organization and seem to have the most jobs. Here is what they are offering:

So what I can offer you for the assignment in San Diego is :

Base pay of $21 per hour, plus $2/hr shift diff. = $23 per hour ...I'll be on night shift.

Plus $35 per day tax free per diem which equals = $245 tax free per week

Let's say I got you $2000 per month for housing-- $2000 x 3 mos on assignment = $6000 in housing, divided by 13 weeks you are on assignment is $461 per week that you would get for housing weekly that is tax free.

Now, take the $23 per hour and put that into paycheck city, along with the 36 hrs- you will net $606.01.

$606 plus $245 per week Daily per diem, plus $461 per week for housing = NET PAY OF $1312 per week.

This is more than what would equal to $50 per hour.

Now, I make at base 56/hr in SF. Am I being low-balled here or is this a good offer. I realize the lower the taxable income the better so 21/hr doesn't seem bad. I used to travel in a different health profession years ago and made more than this, but I realize the market has changed and there are a lot less jobs. I also figure if I like it I'll go full-time. Any advice would help. Thanks.

p.s. I love that it's sunny and 70degrees in SD right now:)