Water-stable organoaluminum compounds in which aluminum is part of the aromatic ring
You're probably not going to get what you want putting aluminum into an aromatic ring.  Aluminum and carbon have relatively poor pi overlap, so your ring will not have the full delocalization necessary for string aromatic stabilization.  And even strong aromatic stabilization may not be all that strong compared with aluminum preferring to bond with oxygen or nitrogen rather than carbon.

Instead of trying to design a compound that somehow tames the reactivity of aluminum-carbon bonds, choose the right polar solvent.  Protic solvents are bad.  According to Wikipedia, organoaluminum compounds "readily form adducts with bases such as pyridine, THF and tertiary amines. These adducts are tetrahedral at Al."  The named examples are aprotic and coordinate through nitrogen or oxygen.