By the following webpage 80 amps is the high end (for a 10 foot run) of what #6 gauge cable will carry. At 90 amps the recommendation goes to #4 cable:
http://www.amplepower.com/primer/gauge Anybody know what size cable Heartland installed for power to the hydraulic pump motor?
BTW, crimp connections when working with high currents MUST be done properly to ensure proper system operation. One troubleshooting technique I have used on low voltage/high current circuits is to run the system under load for a few minutes (run the slides in and out a couple of times) then grab every crimp connection you can on the system to see if that crimp connection is heating up and needs to be re-done.