-The spider harvester warp dock is on the harvester floor, either above or below the stairs.
-Once unlocked the spider will be summoned planetside just above the stairs that go to the factory floor, upon warping the spider will teleport back to this point.
-You can walk inside the spider giving you another surface, within the surface there will be two exit "doors", exit the spider planetside or edit to the harvester floor
-The whole SpiderSurface(SS) would be a pseudo grid. The spider entity won't have a grid as we know it but if you place a turret inside the SS the spider will shoot that weapon. Meaning if you fill the SS with turrets it will become a walking doomsday weapon. Lasers, gun turrets, artillery, flamethrowers, any modded turrets.
-Or as the name suggests: "harvester" placing miners on the SS will take the miner's range and apply that range around the spider, the spider walks across copper and the miners within mine that copper. Supporting modded miners. Well you've heard of world eating worms, now we could have world eating spiders.
-Other pseudo grid things along side miner and turret could be done like using furnaces (their craft speed) would add onto the spider's walking speed, batteries could be shields.
-I don't know if the last 3 ideas are even possible but I can dream and would love to see such magic

Edit: just put the spider surface on the harvester floor so you don't need to make another surface, having the pseudo grid on that floor