So, if landing on a "base" with "few" defenders, and then marching toward an other base is allowed? fine. Having some rules, and understanding them to respect them is "fair".
First you will have to capture the base with the "few" defenders and force them to withdraw before you will be able to advance to another enemy base.
It seemed evident that my opponent (AI or Human) won't help me by saying "Ok guy, you can cross our position, and going to wherever you want as long you don't ask our beer reserve !" .
I think the Pacific war was some kind of fight this way: invading point, fighting for them, so as to use them as base against other base, bombing them, invading them, fighting for them, so as to use them .......and so on.
So the expression "hoping island" (right?). In french we would say "jouer a saute-mouton" ("jump over sheep"). Or even "faire des sauts de grenouilles" (make frog-jumps).