Thanks @Diesel911, I do have that skinny oil supply line (green arrow). It is a lot thinner, but is likely quite brittle. I'll look at swapping that too.

Thanks to the others for sourcing options. I'd not yet found either of those sources. Much appreciated.
I'd like to stick with the clear line if possible, so will go that route first. For removing the line, as it is quite hard, I'd think the best rout for removal would be to cut a line (in line with the hose) where it goes over the fitting, as I'm sure it would be a nightmare to just pull off. If I cut it (razor blade), I'd think that would allow me to get it off.