WiGEs are more or less halfway between VTOLs and hovers. Speed is life, because rotor hits or motive hits, respectively, kill those units - motive hits kill WiGEs. And with all three, you can't make a slugger work. So don't design a slugger. Snipers or skirmishers/backstabbers are the go.
Snipers need a turret, enough MP to control the range, and a long-range weapon or two. Sniper WiGEs can't ignore terrain by climbing like VTOLs do, but outside dense hills you ought to have enough MP to find a fire zone.
Skirmishers need the speed to stay out of contact until the perfect moment for unloading an alpha strike, and then the speed to get out of Dodge soonest. Weapons load could vary between one big stick and a bunch of smaller weapons.
So instead of your 80-tonner, try a 40-tonner with a turret-mounted PPC, or a bunch of medium lasers and SRMs.
Alternatively, WiGEs make great transports for your infantry and BA.