Can you reduce your power consumption in any way? You havent mentioned the 1000w much so i assume there's no issue with that one. Are the 600s for flower or veg? Could you veg with lower wattage fluoros or something?
If its only another month and you're outta there, and if the other breakers are dedicated to the 600s, then i dont see why you couldnt split it up to have each 600w on its on breaker, and the 1k on its own, and hope for the best.
Is there any heat coming from the box or the breakers? That whole box is unfortunate, your whole situation is really... i hope the month goes by quickly and you gtfo into a better place for you and your garden!
Splitting things up is safer in your case, you can make your own extension cord for much cheaper.
Do you know exactly which outlets go to which circuits/breakers? If so, isolate the circuits and dedicate each to one light and ride it out a month.