Don't stop looking.
And don't assume he's having a great time...he may enjoy your backyard, but if he went further he may have well been frightened by a sudden noise he didn't know or a big dog and has gone into hiding. When scared a cat can hide for days before being hungry enough to come out...
You said you lived in the country, how "country" is it? Are there neighbors within reach that you can let know to keep an eye out for your kitty? So that if anyone hears a lost kitty meowing they might go investigate...
And don't assume he's having a great time...he may enjoy your backyard, but if he went further he may have well been frightened by a sudden noise he didn't know or a big dog and has gone into hiding. When scared a cat can hide for days before being hungry enough to come out...
You said you lived in the country, how "country" is it? Are there neighbors within reach that you can let know to keep an eye out for your kitty? So that if anyone hears a lost kitty meowing they might go investigate...