Another couple ideas:
Remove all kingdom and guild bonus for guild wars fights as well as remove combo breaker and cascade breaker, make it a true RNG based tactical battle for you against the AI. This will also level the playing field for more advanced guilds so that some young upstart can take them to task unless they play well also. Sentinels should be the only thing that should affect how powerful your invade team is.
Allow for one click completion of sentinels or a slider to complete them to a certain point.
A log to see your guild wars defenses and how your team did.