I don't handle misdemeanor cases, but I'm familiar with the usual process. Judges don't want to waste jail space on stuff like this. It is likely that he will incur more fines and more court costs.
If he can't pay the fine and costs, the judge may give him a couple of weeks, maybe a month, and set a hearing for him to appear and pay or explain why not. If he fails to appear, another warrant issues.
This process can go on for quite a long time. Every time he fails to pay, he incurs more fines and costs. Every time he fails to appear, a warrant is issued and he's subject to a search incident to arrest.
Sure, the pick-up radius may be in-county only. But the outstanding warrant will pop up for every stop, so that means handcuffs and a search each time, even if it's just a "catch and release." The faster he can pay this off, the better.