X-2 ballast decision; honest help only

What would you do. Got a Maristar (X-2) 2006 model stripped down. The boat has no ballast whatsoever. Hard tanks are look to be to expensive as do any aftermarket 'system.' My question is the following? You have just enough money to put gas in the boat for the next summer (very poor grad student) you only have 4 folks in the boat, how/what would you do to (the more specific the better) create the perfect wake. (we are all used to riding behind a ps 205 (2000 model, samel hull as the X-1 with 700lbs. in the stern and a couple hundred in the bow) thanks for the help, we liked our old wake and would like something similiar.