Not familiar with Wattman, but from looking at the website I'm not sure why you need Afterburner, looks like Wattman can do GPU clocks/memory:
Radeon WattMan is AMD's new groundbreaking power management utility that controls GPU voltage, engine clocks, memory clocks, fan speed and temperature1. Radeon WattMan is based on Radeon Software features but offers multiple new ways of precise overclocking controls. With the new control over voltage and per state frequency curve for GPU clocks, comprehensive tuning control is now available.
Or do it like I did, buy a $20 Kilowatt and find out how many watts each card is using based on TDP %.
Wattman is a sad pathetic joke compared to Afterburner - that blurb about "groundbreaking" is a flat out LIE, Wattman is LESS capable than Afterburner was YEARS ago.
Try setting a fan CURVE on Wattman, for one major issue with it. Capability doesn't EXIST.