The GIV like all other Gulfstream models is very easy to keep within CG limits, a Pax load of 4 would almost certainly be within CG limits regardless of where they sat within the cabin, and so long as one starts within the CG envelope it is impossible to take on a fuel load that would shift you outside of it.
As far as control checks go, in recent years a "Bungee check" of the elevator controls was added to the line-up checklist for legacy Gulfstream models (G2 through G5) which involves pulling the control column full aft and then releasing to ensure it falls full forward with no bounce. Not sure if all crews are complying with this though.