Roguebook

If you're around the 95% mark on the achievement tracker and just want to get the achievement over with then it's worth noting that the gold piles respawn on the map after you mulligan ( during a battle - main menu then continue.) Leave all of the gold piles on the ground in Chapter 3 (the piles are worth more there) complete all of the regular and elite battles then uncover as much of the map as you can with the inks & brushes. After that pick up all of the piles and then go to the boss, mulligan then repeat. The gold will count right away on pick-up, the boss battle is just to reset them, you'll be on the map again along with all the same piles. I was getting 561 gold total each go.
I had the Epilogue called Greed is Good (all gold piles are revealed) on at the start of the run (part of the solution to getting the runes of sight to show a scroll more often) which is an important part actually since you can walk around without picking up the gold unless you press (obtaining gold results in 3 damage to both heros.) Obviously you'll have to be selective till Chapter 3 but your health can't go below 1 from the gold so you can pick it all up at the end and then heal with a bunch of heart containers if you want to actually fight the boss too at some point.

The best case scenario for this is coming across the Imperial Camp event in Chapter 3 (Swear an Oath to the Emperor to reveal the entire map) cause you'll probably get around 1k gold each go in that case.

Another lucky chance would be to come across Khalim's Boots (in any Chapter) which would let you run around the map at high speed to pick up all the piles.