An EV is not light weight in comparison to a gasoline vehicle due to the battery weight.
Efficiency in traffic for an EV is actually quite good. Unlike gasoline the EV efficiency actually goes up to just idle along. Air conditioner is also very efficient. LEAF has a variable speed compressor driven by a three phase inverter. My RAV4 cycles the compressor but still it does not seem to take much power. So on a hot day stuck in traffic you may actually gain additional range. My truck/trailer is terrible on gas in a 6 to 8 hour traffic jam in the heat... and I have done it a few times.
Yes resistance heat takes a toll on range. Best to crank up the seat warmers.
The EV air conditioner also has an eco mode to reduce consumption.
The battery capacity is 5 to 20 times the size of 2oldman's and you are not cooling an entire RV.
Not perfect for everyone however most real EV drivers I talk to cannot imagine going back to internal combustion. They really like the way it drives, low maintenance, effortless power, low cost of fuel and convenience of home refueling.