Don't we have a Hessian fleet (or a hessian squad) everyday in Stuttgart and the Omegas already?
It's not that there isn't enough war in Rheinland already, it's that you need to set some goals for the lawfuls to strive for. Holding out in a war of attrition were you are constantly outnumbered will deplete your forces, especially since lawful positions are in the open and vulnerable, while the Hessians and Coalition attack from near and far from secured bases and whatnot.
Give some offensive goals for the RM and allies, then you will see you don't need an "foreign war" there.