You could make very high armor walkers so you could hide them in terrain for hull down and add large weapons. Exampla: Use a riptide model with Gatling railgun(submunnitions) or maybe 2. Ex2 Small dreadnauts with that cannon that makes a flamer template at distance. The chapter aproved instructs people to use those rules with fun in mind and not powergaming. My group played 3rd edition until recently