If you do the "Bitch for the thugs" quest from time to time it should improve the morale. This quest is taken from Jester and appear from time to time.
There is also a way for bottom players who submitted or lost to Scar. During the visit in the camp there is a chance to encounter bandits. If you 'comply' it will also result in increasing morale a bit.
Also doing "Supplies for camp" makes it that morale won't drop bellow certain point.
I will add some more things to improve the morale in the future, for now there are only those two.