I've hooked up 6 times on Threshers (That I positively knew of), but have only got three boatside... and only kept 1. Every time was something totally different than the next.
1st one was in the Boma, when Roger casts out a fly lined live mack looking for a yellow. The local yellows were in 70 feet of water at the time and he hooks something big!. Long story short, after 2+ hours of fighting it, Roger breaks a 220+ pound Thresher free at boat side since he did not want to take it on board such a little vessel.
2nd one was in 35' of water at the inside kelp edge only about 300 yards from the beach looking for calico. I hook a 80 class Thresher on a 6" Big Hammer on big bass gear. I get him boat side after 45 minutes, and snap him off when trying to figure if and how I was going to get him in the boat safely.
3rd one was trolling a Bait-o-matic in the canyon with a live mack pinned on. Trolling at 3 mph and Bam! Fish on! Fought for 10 minutes before it unbuttoned. Bigger model T.
4th one trolling on the Bait-O-matic in another canyon on Don's boat. Outrigger rod went off with a mighty *SNAP* and had him for one jump before throwing the hook.
5th one was fishing in my boat off LaJolla (105') with a yo yo iron. Must have hooked the tail on a tail slap as I fought him (maybe 80-100# model) for 45 minutes before stupid treble in his tail bent out and he swam off.
6th one was on a f@cking shrimp fly while rockfishing with Steve (115'). I sent the fly down with a squid strip attached and felt a pop on the sink. I thought it was a mack and stopped the drop to catch him. Well, he ate it and up came a 60# thresher that Steve and I boated as it was just small enough to do it safely for the Boma.
So basically Eric, I wish I could tell you what they bite best on when close to shore, but I've hooked them in all sorts of weird ways. I agree a live mack is the probably the best option. Offshore, is definitely trolling live macks on a Bait-O-Matic. In hindsight, I probably have hooked more, but was not able to ID them, but they have little ass mouths compared to their body size, so choose your baits accordingly.