A Mobile Colony? What, are you going to build a new bare-essentials base every 5 minutes? Even on a larger map, this wouldn't exactly work.
LoP, that position is alright, but the lava is still really wide and there isn't many spots for a choke-point. In addition, there is no reasonably close rare ore. Well, there is. There's two. One gets lava-fied and the other is just barely covered.
So assuming we want rare ore, there are 4 locations.
1: We can cheat for the purpose of getting the Rare Ore mine that is just barely covered by lava in the U-area.
2: We can build at the spawn point (our colony is doomed!)
3: We can build in Australia.
4: We can build in the centre of the map.