with the clear fuel line, if it's for the perminant plumbing, it isn't going to be an issue, sure it's hard, but if it isn't going to be bent after instillation, what's the big deal? if you take the proper precautions it'll be fine, and is about $.15 a foot if you can find it in bulk instead of around $1.25 a foot if you can find it at the right price (recently found a hobby shop with it for around that)

almost all tanks are HDPE or LDPE, the only thing that changes between gas and glow tanks is the stopper and clunk fuel line, clunks are metal and aren't going to be an issue...

many have been running the gas/glow combination for a long time with no issues with the carbs...