Not sure what you mean by "45 degrees". Jacks need to be holding weight vertically straight up and not at an angle.
Perhaps what you mean is that your idea is to mount them so the access up/down adjustment port is not pointing straight out towards your sides so that they are less visible(?). That is fine but probably not necessary. It might be harder to mount them to the frame if you try to angle them that way. But if you did, as long as they are securely attached to the frame it would be okay.
If the purpose is to use these to level a few inches here and there while at a campsite, it should be fine (Pending input from others about my question above regarding mount location and potentially bending your frame). But you will want to make sure the weight carrying capacity of whatever jacks you use has plenty of margin and you shouldn't go underneath your RV with just these jacks holding it up.
-Chris