Nate30,
I've seen ride-alongs go down many different ways. Based on your other posts in this thread, I'd say you are not on a daily ride-along .... You are a tag-along for training purposes.
The most effecient way I've found is to look at the route for the day with your trainer. Find the job that should put you in hour#8. Before you hit your first job, drop your car off near there in a store parking lot or in a convienent parking spot on that street where that afternoon job is.
Now the two of you are in a ride-along. Go hit that first job, work the day and if your timing is right, you should be at your car by hour #8 on your afternoon install.
Speaking up for your employer.... I can see why they don't want more than 8 hours a day during training. It's much too hard to try and explain in a post here, but trust me... do JUST the 8hrs each day and no more. I've been in that situation before, both as an employee and as a manager. Seen both sides of the fence so-to-speak.
GL on your new gig.