Here we have the trolley, complete with nose pad!
The more observant amongst you will note its angled, there are reasons:
1: so I know which is the front
2: so it wont fall off the back
3: the water at my club has a launching ramp and the idea is that the boat will enter the water stern first more or less on an even keel.
Regarding ballast, yes its all as low as possible, but not all centralised, there are some lumps of lead that go over towards the sides, evenly about the centre line. Three reasons:
1: couldn't get it all on the centreline
2: seems the right thing to do
3: real ships don't have all the ballast on the centreline, so I guess it must be ok.
Ian