An easy way to get new maps is by just taking them from other games.
Ofcourse they have to be suited for SG.
I have found the Soldier of Fortune 2d CTF gameplay very similar to the SG BR gameplay, and have been thinking about the maps. And imo some maps seem perfect for SG BR mode.
Some maps could use some change in looks, but one map even allready looks like it is an SG map.
But for most maps a little change like some different buildings, or some SG crates and barrels instead of bushes etc are enough.
This way a mapper could make 3,4,5 new maps with a couple hours(?) work.
These maps are proven to be balanced and they might add something new/extra to SG BR. Also because they only have one spot for the Gold, not 2 like in the existing BR maps