An AI will do very little to reduce the bloat from Deca as far as estrogen is concerned (keep reading for more on this). However, it will reduce the estrogen conversion from the test that you SHOULD be taking alongside it.
The bloat from Deca is likely a result of enzymatic inhibition (which I know to be the case with madol), which may be tied to progesterone. You can reduce this bloat by cleaning up your diet, cardio, increasing your potassium intake (as opposed to lowering sodium), and using a (mild) diuretic.
BTW, dopamine agonists like Caber only lower prolactin secretion, not progesterone. However, progesterone secretion from the adrenal gland is directly tied to estrogen, and they are both lowered by AIs. So therefore, an AI should help with Nandrolone bloat, but just not through the mechanism that you were thinking of.
Oh, and "Deca" tends to cause more bloat than NPP because it is a longer acting ester, so it reaches higher peak concentrations during a cycle.