I had two 27 series in bow for trolling motor batteries, 1 - 24 series in stern for cranking. Worked good. Until I swapped out the four stroke 50hp and 21 gallon fuel tank, for a 2stroke 25hp and a 6 gallon tank.
All three now in the stern.
Always open respective compartment when charging. Haven't had any issues with any other gear.
Now that I think about it, I've moved those batteries around 6-8 times!