Mine is KINDA like Walls, only with a twist - you'd still have the partition in the middle to prevent artillery strikes from levelling bases in the first 3 minutes, but I say put the bases on hills about half the height of the one in Hourglass so rushes are somewhat slowed but not stopped. Plus the higher vantage point would allow reconnoiters much further into the distance.

But what about the TUNNELS? Simple. Make them longer, and you'll have to wind your way up. It should discourage early engineer/tech rushes but not stop them entirely...