Well, there are a variety of EMS positions that have fairly regular hours. Some people work in hospitals. Some people work in school, on movie sets, construction yards, amusement parks...I myself work one job in an Amusement park...it's fairly regular hours and lots of fun. There are also private agencies that transport people from one facility to another.
There are many, many options for work in EMS that are fairly standardized hours. Most places are different, but there are still options if you look. However, I would recommend shadowing some EMTs, nurses and respiratory therapists. The last two jobs make 2-3 times more than EMTs (unless you also work as a firefighter). Any of those jobs will let you shadow someone for a day. I'd just call a school in your area and ask for the program director, and then ask who they recommend shadowing. They should give you contact info (because they want you to eventually join their program).