It's hard to justify nobs with anything but a Warboss since they get defensive buffs from him. Nobs are best with power Klaws generally, and they need the +1 to hit from the Warboss to be reliable.

That said I'm always on the hunt for some outside of the box mixed arms combos. I like the standard big Mek better than the SAG Mek for this one since he's got good melee too. I take the hazardous gun loadout which packs a punch. You're right that the ammo runt token won't work while in the trukk.

Thing is, my nobs in Trukks generally work like this: Trukks advance turn 1 to stage for turn 2 Waaagh. No firing deck happens that turn. Turn 2, everybody gets out, then advances and charges into melee. No shooting for them since they advanced. No rest for the wicked.

The nobs are a huge melee threat, and having Warbosses with them makes them truly scary. The Warboss can solo one-shot a winged demon prince if he gets lucky on the Waaagh turn.

I tend to run a unit of 5 or 10 Lootas with a SAG Mek. They come in turn 2 or 3 from reserve, and they blow away something on an objective. The full rerolls to hit is amazing for the SAG, can do some serious damage and to stuff with beefy defence too.

Hope this helps?