Replace copper lines under my Trade Wind?

[coairstream]

I have a 1972 Trade Wind and had to drop my belly pan to remove my fresh water tank. Because it was in the way and I think I damaged it I had to cut my coper line that runs to the front of the trailer and hooks to my regulator. My regulator is old as dirt so I will already be replacing it.

My question is this:

1. Should I replace it with copper again or use the rubber type hosing like what will go from my regulator to my LP tanks?

2. The copper gas lines that go from my Axel going back I will probably leave alone as they seem to be OK, or should I redo them all, or at least replace them all to the point they run up into the interior on the coach?

Thank you,
Cody