I weigh about 175 and probably have a couple of inches in the footwell of my Outback. It doesn't cause me any problems, so I have never thought much about it. Here is a pic of my footwell for comparison purposes. The blue arrows denote the water level.
One thing you may wish to consider is adding some flotation inside the hull. This is easily done by placing some foam pool noodles (mine came from Wal-Mart) inside the hull. I carry 8 in mine: 4 thru the forward hatch and 4 thru the after hatch. However, I don't carry any rods or other gear inside the hull so there is plenty or room for the noodles.
Here is a pic thru my after hatch. The line on top is a spare anchor/tow line that I sometimes carry also. I can't honestly say that the noodles make much difference, but they may, and it is an easy thing to do, so why not? Who knows-if I get plowed into by a CPB (i.e., a crazed power boater/jet skier), I may be glad to have had some extra flotation inside the hull (assuming I survive the experience)!