Don't fret too much about the torpor decay. It's actually not that bad even though it's scary when you look at it. While the decay rate is incredibly fast. The recovery rate of narc is extremely slow comparatively. So while you'll have to rush it to drop you tranqs, wait until the torpor is quite low (I've been told 100 but I don't trust my lag as much so maybe 1000 before pumping it back up) you'll then have the easiest time in the world to tame it as you'll easily have 2 hours before you need to come back and put him to sleep again.

Make no mistake the difficult part is actually putting a ko on the creature. If you got two player the cheapest way that'll work is to have a person on flying mount hoist his buddy with a grappling hook.

Bring spare weapons with misses and the crazy torpor decay, the estimated number of dart to take him out is wishful thinking at best.

Solo, make 4 metal Dino gate + bear traps.

Bring sleeping bag / bed you'll need them.

If a Giga is what you desire

Then to the skies you must fly higher

Hundreds of tranq arrows and narcotics in your pack

Fired from a quetzals back

A sleeping Giga you shall soon acquire

Whilst the Giga is laid to rest

Waiting for torpor to be low is surely best

Because while it may wake up quickly

It cannot wake if it's still getting sleepy

Don't worry about wild dinos they surely will not test

Quetzal kibble is it's favorite treat

But if it wakes up you're next to eat

So be vigilant during the tame

It's quite the waiting game

But when it is yours you won't be beat

Okay, your only hope of knocking this calamity with legs out is by running it through a gauntlet of tripwire tranq traps while hurling shocking tranq darts at it. I would even go as far as saying just use the about twice as many tranq arrows you would need just because there is no risk of death(lol) and you would have better fire rate, it would just take longer. BUT according to here, this industrial excavator with teeth loses torpor at a ludicrous speed, so maybe if you just made dang sure not to miss, you could forgo the fire rate and use the shockers. Maybe run it through a gauntlet jumping over the traps so that he hits a trap, you shoot him, he hits a trap, shoot, so on and so on… pray to Ark Jesus this works…

When wild has 80k ish health, drops down to inbetween 16-18k when tamed, but if you still want to tame the gigger, just stuff it with tranquilizer darts from a 150 plus gun, feed mutton, if you want to trap it, use small metal gates, do NOT use anything less than a good gun! I hope this helps your giga taming. -TheForceTameSpiter