With 2 in series, the 3 pairs in parallel, that's 0.33 ohms.
Dumping at 28.8V, that's 86A, which is way past the 60A the controller can handle.
That is a total of 2488W, or 415W in each 300W resistor.
Not good.
Wired 3 in series for 1.5 ohms, then paralleled with the other set, that's 0.75 ohms.
Dumping at 28.8V, that's 38.4A, 1106W or 184W per resistor.
That's fine.
Except that's pretty light on the dump capacity for a 10', unless you furl early like recommended, maybe round 800W.
It would keep the duty cycle down, so at the worst the resistors would be averaging about 134W. The 300W resistors will not get super hot with 134W in them.
I would not want that box sealed with a lid if it was mine.
That 800W average is about the same amount of heat as some of the Hi/Lo 1750W electric heaters set on Low. Meaning still quite a bit of heat.
"How do you connect the incoming wire from the dirvision load controller to the heating unit?"
Uh, crimp-on ring terminals?
Not sure what you mean. I'd bring in a heavy wire, join it (I'd solder them) to 3 lighter wires to go to the resistors.
I used brass toilet bolts with the goofy heads. Long, cheap, and available everywhere.
The holes in the resistor's terminals will need drilled out, just a hair.
The extra nuts will hold the wire out away from the heat. Common wire would be fine, IMHO.
Don't let wire touch the ceramic part.
I considered adding another pair of nuts and a brass fender washer half way between the resistor and wire a time or 2, sort of like a heat sink, but they were not needed because I design my stuff to stay cooler than most people do.
G-