Hey are you taking air units into consideration when suggesting these things? Also, whats so bad about having six minerals at main and such? Lost temple only has seven at start and its a four player map.
Hey should i make the northern part an island and make it a channel to both bases?
Air: Sure I guess so. Either way two thin pathways across a land map is not much at all.
Minerals: LT is 4 player map that has 8 at main (2 more than yours), 7 at natural(same), and 6 at the min only. Since its four players, and mostly used by two, it has much more, and they are alot more accesible than yours. Besides, most two player maps have almost as many as a four player map does. In most of my LT 1v1 games by the end all but 2 expansions are used.
Island: If you made it an island, I would make it land accesible (it also wouldn't be an island anymore).