What do you think about getting the frame rino lined?

There are better linings than Rhino, but they are still not what you are looking for. Besides, they are not really for "rustproofing", but more for protecting surfaces that see lots of abuse, like truck beds.

You would be better off with something that is intended to be frame paint. POR-15 makes some really good products and there are some really nice industrial paints out there that would serve the purpose.

Good Luck,
Michael