My exhaust guy said he won't install tail pipes if I use rubber (or nylon) hose near the axle. Plus I might need a larger line for more HP. As long as it doesn't burst or leak I can't see why it wouldn't be safe. If I get in an accident bad enough to break the hard lines, I'll be dead anyways.
As for an accident, you SHOULD have an intertia switch. Do you? If so, it will kill power to the pump in the event of an accident.
The exhaust temps clear in the rear of the car are very low. Definitely way too low to melt these lines. The line also shouldn't be within a few good inches of the exhaust anyway. So I wouldn't even worry about that.
According to your signature, you have a pretty mild, nearly stock engine. I have all the most listed in my sig and the donor car (that I got the engine out of) was running stock line. It was plenty for the mods I've got.