Well you could buy a cheaper used bicycle,
Then ride 8 miles in your truck and bike the rest of the 8 miles till you get in shape. That would cut your gas bill down to a 100 bucks.
You really just need to ride do a search here, and pick for yourself. Me Toruing bike due to , my load and mostly road.
As for road choice, there are several things you can do for a single lane road, ridding technique, mirror, vest, ankle reflectors, flag, lights, etc. These all will help you feel more comfortable and these forums have talked about them over and over again.