I just finished doing this on my 1913 - I took a 5" vinyl fence post from Home Depot, cut it down to about 7 feet and mounted it to the frame rail and used fence post caps secured with a 6" bolt and wing nuts to. I used a section of 4" rain gutter as the 'tray' for the hose. So far so good. It holds my 15 foot hose with no problem but there isn't enough room for my 10' extension hose.
If i had to do it over again, I'd cut the fence post so it was a long as could be without extending past the trailer walls - this would add perhaps another 12 or so inches and might allow both hoses to fit.
Just me, my girlfriend and our crazy Boxer Stella.
'13 GMC 1500 Sierra Denali, '14 Stealth SS1913, '08 YFZ450 with some crazy engine mods.