For starters, don't recreate the wheel, the reason most people use the iCharger is because they have proven their worth to thousands of racers around the world. Next, the RCdischarger just seems like unnecessary complexity and cost restricting your options.

Good news, the newer iCharger models, like the 456DUO, have an program option for programmable POWER output, offering adjustable Voltage and Amperage from Channel 1 or 2. So if you need only need to charge 1-battery at a time, use Channel 1 for charging, Channel 2 for power to your tire warmers. Another cool thing with the iCharger is that you can use it to charge Pb batteries (lead acid), so you can use your iCharger to charge a standard 12v automotive battery as well.

If you need two channels for charging, then you need either need a power supply with multiple outlets, like a Muchmore CTX-P for example, or a power distribution box like the Muchmore Power Supply Station Pro Multi-Distributor Box w/USB.

For discharging, get a standalone discharger, the ISDT FD200 or the Hitech/SkyRC AD380 or BD380 work well with the ISDT being limited to 25A discharge, the other two 40A at more than double the price and double the size. I mention a separate discharger as you can pull that out anytime you need to discharge those batteries you may have run out of time to discharge before leaving the track without having to pull out your power supply, wires, etc. Additionally, when you have a discharger failure, or a power supply failure, as you might encounter with the RCdischarger unit, you can replace just one thing and get back racing.