Hoth is way too big, Genonsis is better. Also its a easier target at long range, since you only need to be in front of that ATTE.
On REMEMBER TWO THINGS:
1) DO NOT LOCK ON TO YOUR TARGET. DO NOT do it I repeat. It will falsely guide your shots away from the critical hit spot most of the time.
2) Go to Elite mode, for the same reason above, avoid the stupid computer auto-targeting help, which tend to cause shots to go off the critical sweet spot.