if you have more work than your business model can handle, you need to raise your prices because, well, its apparently worth it! This WILL have some people drop you, yet the price increase will cover the lost clients (10-20%)
if you continue to grow past that, you need to hire out and get some other hands doing work for you.
I have a job down in Del Mar tomorrow, its 1.5 hours from my house...better believe he is paying for my travel time. There is no way you can operate at 3 hours of "dead time". So what I do for my "out of area" or "too far" clients is either make the trip worth it (minimum Ill go there for), or tell them its going to be an extra $50 bucks. otherwise, it just makes more sense to NOT go there and to book someone else closer for that day instead.
Another thing you can try to do is get help (per day type part timer) and knock out two of those further away jobs in one day. you will no doubt make the trip worth it even after paying the help, plus you get carpool lane!!! LOL
OR, get a more fuel efficient car since the actual issue is the gas money, and not the time. If you are cool with a $200 day, but dont like the $15 bucks in gas spent, get a hybrid or an electric car, or a 4cyl getting 30mpg...that will drop your cost right there if you are driving something in the range of 13-18mpg car right now. I Drive a lot as well, but all my jobs are a minimum almost double your price (but the scope of work is double as well - 10 hours average) so its worth it to NOT charge a mileage fee. However, like when I went to Bakersfield, I made sure there were 3 cars and a total value of xxxx amount to even consider the job...
it has to be worth it in the end to own your own business, otherwise you might as well go work for someone else and work a 9-5 and not deal with the headaches of running a business...plus you would probably get better benefits as well!