Re: additional potable water tank location
Time to start doing a bit of math - no need to go extreme, but you should at least do a rudimentary weight and balance to get a feel for your loading.
I wouldn't get obsessed about sailing on her lines, but you should at least have an idea of how you are changing her floatation.
We once put 400 lbs in a 9,000 lbs boat a 'bit aft' of what we guessed was center of floatation - it lowered the stern by 2" and raised the bow by a lot, boat appeared to be popping a wheelie. Why - Center of floatation was significantly foreward of our guess.