There is a couple of factors you may want to consider.
If you work "Hourly", then you get paid for the amount of time you are ACTUALLY working. This all goes into figuring out the "Bottom Line" or "Over head" you boss has to figure in to make his/her business work. There is insurance to consider (for employees and the business), Electricity (lights and any machines you use while there), Heat, Software/internet (Veterinarian EMR) . . . Etc.
You could try to establish yourself as "Self Employed" but then you would have to take care of your own Health Insurance and work at a lot of places willing to do "Contract Work" (Usually determined for a length of time). You would have to "Specialize" in a field to have this be "Marketable". Then you could charge for "Minimums" and most likely make a little more, but then you ARE carrying your own insurance and other expenses.
You could talk to your boss about making you "Salary" . . . This means you get "X" amount of money annually . . . You DO NOT get over time. So anything over 40 hours a week is free work for your boss. While this sounds alluring, most Salary workers are "Abused" regarding their time. My last job I worked an average of 47 hours a week . . Figure that out annually and then divide it hourly, you may find you are working for less hourly then you were actually getting working hourly in stead of Salary.
If you like where you work, and Hourly is not a problem, but want to make it worth your time, and fuel in getting there, ask your boss if there is anything else you can do to offset the expense you have to get there. See if they can come up with an hours worth of work to do while you are already there.