dual esc/motor setup

[nitrostarter]

Like BrianG stated earlier, Dual brushless tend to fight each other or one system overworks its self. Its hard to dial the systems in perfectly, which in turn can cause as many problems as before.

I think for your truck and what you want to do, hill-climbing and 35ishmph in a heavy vehicle, I say gear it down and try it again. The 1515/1y is a strong motor and geared down to 35mph, it shouldn't have a problem.
Otherwise, a HV system is in your future.