If your plan was to rehome all 3, why do you still have the one? Is it possible to rehome Betty the cockerel and get your other 2 "new" pullets back? The best way to keep your chickens from roosting on your truck or other unwanted areas or being killed by predators is to keep them in an enclosed run. Not everyone can free range successfully.
If you do choose to keep your roo, he will likely need a lot more hens to keep the peace (common ratio is 10:1) even then there will still be pecking order. Are roosters allowed in your neighborhood? Successful integration happens in stages, starting with See But Don’t Touch.
Here's a few articles with lots of good things to know if you'd like to start over:
How Much Room Do Chickens Need
Keeping Chickens Without Free Ranging
Guide to Improving Your Identification Skills
Keeping A Rooster