I was going to mention the samsquanch as a great shield mech, but it looks like you fought it first-hand. The thing is, BV wise the sasquatch isn't bad at all, but if you want to buy it using C-bills? That's not an XXL engine, that's a LARGE XXL engine, something you'd slap on a small craft or mobile structure or dropship. That thing's over $100,000,000 in just the engine alone, all to get it to haul ass with that big shield. I love it though, I have a 3D printed samsquanch in my 'experimental weapons' battalion.