I do have a mechman 270 and a d3400 under the hood with the oem battery and 2 xp3000 in the back and im not droping under 14 volts with a dc 5k so you should be good.
I do have a question though. Would adding a 3rd xp3000 be to much for my mechman 270? Im not dropping under 14volts but would like my voltage not to move at all.