0.75A too much draw?

All depends what all sorts of electronics are on the truck contributing to the parasitic draw?

 

You will have to find out what their spec is before knowing if it's excessive and whether that spec includes ELOG devices, cameras, etc.

 

Depends on what length of time you're talking about. On a car, you want to see <50mA I'm pretty certain, so you're exceeding that by 15x, but have way more battery capacity. To me that seems like a lot, as the modules/computers should "go to sleep" within 20min or so of key off. I would try to see what is contributing to the draw.