Mike,
The problem with the Proteks (and other typical RC chargers, I assume) is that their LiPo storage and discharge profiles require that you connect a battery's balance lead... IOW the charger functions as the BMS.... and it will not work if that connection is absent. There is no straight LiPo discharge profile that works purely just on overall pack voltage. Of course the M2 batteries have a built in BMS and no balance lead. I suppose you could open them up and connect one but these are too $$$ to mess around like that.
I pinged ProTek and they said that you may be able to use the discharge profile for another chemistry like NiMh that only uses overall pack voltage. These are customizable as to amps and cut off voltage. I haven't tried that but it should work. Just be careful to set the cutoff where you want it, something like between 15 and 15.5V.
For now I bought that Gforce discharger from Amain hobbies that I linked above. It works great but it is a shame I had to buy a separate device for this. Why don't the aftermarket charger guys incorporate this feature??
As for connectors just go on Amazon and buy a couple of the cheap
Mavic 2 car dual chargers that can be had as low as $12 and cut the connectors off. I also bought an extra car charger to keep in the truck. Might come in handy sometime to charge in the field.