In Series Using Bullet Conns

I need to run a pr of 2S 5ah batts in series. The prob is they came wired with 5.5mm fem bullet connectors. I've not dealt with bullets on batts before and have built deans adapters to let me do either series or parallel to use.

The wire on batts is 8ga and I'm not sure I want to tackle converting them to deans - deans are pretty crowded for space using 12ga, so I'd rather use the bullets already on the batts. Guess the 8ga is overkill since 125b wiring is 12ga. Nor sure I can get 2 12ga wires in a bullet conn to built an adapter similar to what I have done with deans.

Any easy way to do this?