Two Oxen and a Cart.

That is what you need to carry the loot. (They can carry a total of 10800 lbs.) These guys need to be placed a short distance from the exit of the vault, AND you need to figure out the best way for a small object's weight to be distributed over the cart.

Fabricate the gold into a single cube. It will be a tiny bit bigger than 2ft cube. (Gold is incredibly dense -- a 2ft cube of pure gold is 9712 lbs) Now... for the best part: cast Animate Objects and have the gold float itself out of there. (2ft cube would be either small or medium object) Land it on the cart, and get out of there.


What you really want: 8th level spell, Demiplane. This makes your very own vault you can then load all the gold into and access whenever you wish to depart with some of the gold. As it's on another plane of existence, there's very little evidence to catch you with.