Sorry I hadn't seen this post.
I have seen tanks with multiple triggers, so it can be done. A 75g might be pushing it a little, especially to have 3 of them. You would probably be OK when they're juveniles, but then you'll have trouble as they get larger.
The other problem that you might run into with this particular combination is that the crosshatch tends to be more timid than the other two, and might get abused by them.
I think you'd be able to get away with any combination of two of them OK; I personally wouldn't, but you could. You'd still want to be ready to upgrade to a bigger tank.
Dave