It does not matter if you make outpost ships more expensive and increase the build time. If person is determined, he will do it.
You are actually digging a dipper hall for your self. Because if outposts ships become harder to make, players will find an alternative. They will start conquering other player planers.... Heck, it's way cheaper and faster!

Guys, you need to look at this from all sides. Because it looks like you are shooting your self in the foot here...

But going back to players that play 10 mins a day, vs. 2 hours a day. Well it's ether you play smart or play more, I wouldn't expect a person who only plays 10 mins a day to win...