I don't often fish with balloons at anchor, Ioccasionally usethem when drifting and/or flying the kite. In any situation, I usually place the first hook in the fishes "nostrils" from one side all the way out the other; then place the second hook in the fishes back just behind the front of the second dorsal fin (3/4 back on the fish). You want to be careful to keep from placing the second hook toofar back and "bending the bait", leave some slack so the trout can swim around freely.
I rig with 2 #2 trebels 6" apart, 12-14" #6 stainless wire, 50-75# swivel. If the bite's slow I'll scale down to a #4 hook and just 4-6" of wire leader.
White Trout will slow troll fairly well, if you can go slow enough. You really have to just go clutch ahead to avoid killing them. But if you find yourself in an area that you know there are Kings present, slow trolling works great.
This was Sunday 11 Nov, he ate a 10" white trout