Thanks, it will be a tight fit..
I am not sure it was a good idea to go with contactors, it would probably have been good enough to just have a bms with a switch to break the circuit. These contactors are more for voltages in the 400V range, and they sure take up some room.
Yes, there will be rubber grommets, things are just test mounted at this stage.
I have to find orange shrink tube and orange cloth tape too, but no luck so far.
I have made a cad design for one of the battery covers (cardboard aided design

)
I hope to be able to make a fiberglass mold from it..
I have never used something this unstable before, not sure how it will end.
I plan to make some finishing touches to the mold when it is finished, hopefully that will be good enough.
I got my hv to 12v converter today too:
It seems to be better than I thought
I looked around, and had a hard time to find what I was looking for.
I finally found this at banggood. It did the voltages I was looking for, but only 10A. I don't remember if it said anything about if it was isolated (input to output), or if it said that it was not.
I bought it anyway, when checking I found that it was
In Chinese fashion there was 4 wires, but no diagram or anything. But when I opened it up it was easy to see what was what.
There was also a potentiometer, where I was able to set the output voltage.
I set it to 14,4v unloaded, about 14,2v loaded. That was with about 49v input, I have to check to make sure it doesn't change with 90v input.