I would stick with copper lines, following the same route as the old ones. Rubber lines are tough to make ends for and tend to chafe, which is bad for a spot where you cant make a visual inspection. Resist the temptaton to use compression fittings. You will need to make double flair fittings on each end of the new tube to stay up to code and stand up to the wiggling, jiggling and vibrations they are subject to.
A decent double compression tool can be bought at an autoparts store for less than $40, its the same joints used for stainles brake lines and what not. It will require some practice if your not familiar, so make sure you buy extra tube
Chances are the remaining lines are fine, I only had 1 fail on my trailer which is 10 years older and only used single compression joints.