I don't think any more options to increase cohesion are needed. I mean, you can train your troops, treat them to entertainment, and there are random cohesion increases you can get free. I don't see why another option to increase cohesion is needed. If you can afford to spend gold on making your troops better, you can afford to pay them more each week.
But, for your situation, I'd choose light training. It is fairly common to get an increase in cohesion without increasing training. Sure training % might go up a little, but that's not going to increase their weekly pay by much.