The easiest way is to just tuck the long hose under right side of wast strap. I have been doing that before I have a can light. I think it work even better than routing under canister.
Looks like Hollis Elite harness is very similar to DiveRite Transplate. Hollis solo is basically hogarthian harness with extra pair of shoulder d-ring. I made a switch from transplate to basic hogarthian, I think it is a improvement in comfort and stability. Extra pair of shoulder r-ding actually make more confusion because you will not remember which d-ring you clip what gears onto, so you won't be able to retreive your gear without looking.
You have all hardwares you need for hogarthian harness from the elite, why not just go buy 15 ft of webbing. It should NOT be more than $15, give basic harness a try. If you don't like it, you can put the hardnware back to your Elite, and only wasted $15