"If everybody is thinking alike, then somebody isn't thinking."
Which would you find more appealing? I see the game as being relatively short but obviously full tactical battles would prolong it and change this a lot.
First reaction -- skip the tactical system.
Do your players represent a sort of Grand Exalted Overlord that controls the destiny of a nation or a civilization?
Do your players represent some type of nebulous "command structure" that controls political, military, and diplomatic elements?
If the answer to either question is "Yes" then avoid the tactical battle board. The magnificent Supreme Leader does not coordinate the actions of individual space ships in far-away regions of the galaxy. The wise and powerful Great Pooh-Bah should direct the fleet to the appropriate area and await of the results of a "quick & dirty" battle system before making the next strategic decision.
My 2 cents.
Good Luck with your prototype!