Plus amp/watts and ohms = utter confusion to me.
Volts x Amps = Watts (power consumed) - can your alternator / generator / stator provide enough power
Volts / Amps = Ohms (resistance) - resistence to current flow
Volts / Ohms = Amps (current drawn) - can your cables carry this much current
Amps x Ohms = Volts (potential difference) - proportional to current and inversly proportional to resistance, don't worry to much about this one on vehicles.
Know the current your heater is going to draw, and have an appropriately rated fuse - the fuse is to protect the cable not the device. Ensure that your alternator / generator / stator has enough power to spare to start and run the bike, charge the battery and run your heater.
Your alternator / generator / stator is largely none upgradeble (it is but for pratical terms it isn't), but you may want a better battery (practically you probably won't).
If memory serves correct the K1300 is a 12AH battery - meaning you can draw 12 Amps for 1 Hour until it's dead. In reality you can draw a lot more current over a shorter period of time (think starting it up) that won't hugley deplete the battery, but with this to recharge AND the load of the heater, you may find that stop start trips in cold weather can leave the battery struggling.
Suck it and see I'd go with (don't suck the battery
)