I replaced the head, holding tank and sanitation hose 2 years ago. I used the Sealand Odor Safe hose. However it is difficult to bend. My mechanic was showing me an 'odor-free' sanitation hose last year that was far more flexible, however not being in the market for it, I failed to obtain (or more accurately REtain) the make/model.
To remove, what I had to do is this:
1) Removed the hose from the head. Then stuffed with an old rag as tight as possible, then duct taped the thing like crazy.
2) Removed from the holding tank and did the same.
3) Pulled both ends into the locker in the mid-cabin.
4) Pulled the entire length of hose into the mid-cabin.
6) Like a man with his hair on fire, out of the mid cabin, up into the cockpit, out of the boat and straight to the dumpster. I'll buy some new rags.
NOTE: Keep the ragged/duct taped ends at the highest point as much as possible.
I was lucky enough to not spill a drop, but there is a high 'pucker-factor' involved.