If you're going to be in the Springs, you should go to Rocky Mountain Brewery near Powers and Platte. Its one of my favorite breweries in town. Trinity is my absolute favorite though and is a must visit.
I wouldn't water it down, but just alter the recipe for a 4 gallon batch. If you do a 5 gallon recipe with 4 gallons, I think your yeast might have problems trying to work in that high gravity environment.
But I've only done a few batches and am still learning so I might be wrong.