So yeah… after a whole afternoon on the water, came home to recharge all of the battery packs, and can still confirm that the standard supplied battery and the couple of TURNIGY packs WAY outperformed those OVONICS “performance” batteries. 
Stock and TURNIGY batteries still showing 3.46-3.6V per cell after the LVC cutout kicked in, whereas the OVONICS were all WAY below minimum, with great patience to even be able to get the boat back to shore at less than 3.2 volts across each cell.
Was a waste of time making that DEANS/XT60 Series lead, as wasn’t able to physically fit the two hard case OVONICS 5200mAh 50C 2S batteries within the Hull. 
Gonna go all hillbilly mechanical engineering on them and cut open the hard cases, remove the LiPo cells within and simply tape the bastards together as a stacked pack in single configuration.
Recharging everything now, but the standout of the day was my ancient old TURNIGY 2200mAh 20-30C 3S with the dodgy Ohm cell resistance way outperforming the brand new OVONIC “performance” batteries. 
Plenty of leftover voltage after the LVC kicked in, and recovered amazingly fast on the SKYRC Charger.
Got to fiddling around with the Hilux Dual Cab while attending to the multiple battery charging chore, and I think have finally found the ideal candidate for the MKT Monster Truck wheels.
Like any project, same with the Gelblasters, gather a big stockpile of aftermarket parts for “planned” builds … but then find out that nothing ever goes to plan, so just keep mixing and matching/trial and error until the end result finally reveals itself!
So yeah, happy with the scale looking results on this, even though the parts were meant for a completely different build, that didn’t work out but this kinda does!
Never seen a HILUX Monster Truck before, but if there was one, I’m pretty sure this is how it would look. 
Disassembled the rims/tyres and removed the shitty internal foams, leaving some decent quality soft pliable tyres to work well on this lightweight vehicle.
The aftermarket brushless motor/ESC/3S power train along with the aftermarket 2 speed Alloy/Steel gearbox and Portal Axles has more than enough power to turn the bigger tyres with a shitonne of torque. 
Will keep swapping and trying out many different aftermarket parts between the many different model RC Crawlers I have in the fleet until finding what suits what the best.
In the meantime… absolutely destroying every single LiPo battery I own chasing ducks at the local Weir. 