I love Cragtop Archer. You can make the range MUCH further, though. There was a thread on WotC's site exactly for this purpose. Also, Horizon Shot only lets you make 1 attack as a full round action, it's not quite as god as you're making it sound.
And only in super twisted "strict RAW with no room for sanity checks or RAI" is shooting a mile requiring of a spotter. You should be able to see a mile away just fine. Picking out targets would be tough, but I guess that's what
15 range increment penalties is supposed to simulate...
You do NOT need a spot check of 20 to see 200 feet away, you do not need a spot check of 200 to see 2000 ft away. Those rules are purely for spotting hiding creatures and (IMO) are very, very flawed even for that.