I had a lot of rust on my astro... ended up having to run lines on it... that was a 1st... and because it was an ABS van the master junction box sat under the drivers seat (under the body)... the passenger front line died and I ended up running 2 pieces of the pre-flared stuff... outside of removing the engine I don't know how it could be done with a 1 peice line...
I barrowed a friends bending tools... he had the simple cheap one and a higher end one... I honestly prefered the smaller cheap crappy one...
then once that one was fixed the rear line died... because it ran between the gas tank and the frame rail (prob inside the frame rail C section) i ended up routing it around the other side of the fuel tank... hung it with rubber covered bolt on hose run thingies...
also the fuel line from the fuel tank to the fuel filter died... all of this was due to rust... so I picked up a fuel line repair kit... unfortunately that would mean pulling the fuel tank... so I ended up running the replacement line from the filter to close to the fuel tank line and used a few inches of EFI hose with double hose clamps on each side.
move to a month or 2 ago... a friend calls me with the brakes out... head out to find the rear line is dead right somewhere between the wheel well and the pumpkin where the soft line runs... because of the way the line was run I ended up cutting the stock line up in the wheel well (there was enough of a run that I was able to bend it out to be able to cut and flare it)... the rest I used a pre-flared line...
I had never done a double flare before... I borrowed a harbor freight kit from a friend... had to use a C clamp on the holder portion so the line wouldn't slip out of the clamp... but it worked ok... I just practiced about 4 or so times with the spare line i'd cut out...
yes you SHOULD use a single run if possible... but when you use pre-flared lines thats not possible with a longer run... also figuring out how to get it all in is fun :-/...
if I had to do it again I'd prob just buy a decent flair kit and a roll of line and build it from scratch... a little time practicing with the flair kit goes a long way... cut a little long and you can take out the length somewhere else... or if you fudge it up you can cut it again and still have enough room to fit.
best of luck
mark