Immersion Chiller Leak

So I was doing a hop bursted IPA with sorachi, simcoe and amarillo tonight. Very excited, a mix of hops I haven't tried before. I was on pace to have about 6.4 gallons at 1.070ish. That was the goal anyway. My immersion chiller leak added about 1.5 gallons of top shelf north jersey tap water, though, and I ended up with a little under 8 gallons of 1.056. 6 gallons went into the carboy, and the rest went down the drain with a tear.

So my thinking is... ok... so what? it's fine. It'll just be a little diluted. I mashed at 148 for 90 minutes to get a dry FG, but now with the lower OG I'm thinking this may be a bit low.

I have a pound of maltodextrin around here, but I've never used it before. Assuming I get the ferment I was expecting, how much maltodextrin would you add to this to make up for a potential thinness due to the dilution?

Anybody have any real experience with adding maltodextrin post ferment?

I have had under fermented wort before and tried to fix my adding DME. All I got was more alcoholic astringent beer. Although this might not have been the best solution I don't think any other fix would have ended much different. The real fix for a low gravity low body beer is to brew a beer that has more body than you want and mix the two. You can even brew the same recipe with the same amount of ingredients but a gallon or two less in volume depending on the quality of your present beer.