We have one of those slinky hose supports. Used to use it regulary, but now, not so much.
Reason being: For us, it once caused a nasty mess. You see, the problem with those slinky hose supports, is that when you dump, and a bunch of 'stuff' rushes through your hose, unless you hose is stretched really well in reaching the sewer drain (something you can't do if your shortest hose is 10' and the drain is only a few feet away)...The rush of water will make the hose 'squirm'/expand. When that happens, I've had the hose squirm enough sometimes that it fell completely off the slinky support. One time, when it fell off, it twisted the hose enough that it popped right off of its connection to the RV, then we had a 'shower' of nasty stuff spewing out until I could close the valve back! Ugh!!
(..That was also the day that I learned why its a VERY good idea to use black tank chemicals to reduce the smell of that 'stuff', and that the kind I was using, 'Odorlos', works very good at that, haha!)
Since then, only time I use that slinky support is when the sewer connection is far enough away that I can stretch the hose enough to be sure that won't happen. The slinky support comes with several short rubber 'bands' to stretch across the hose to hold it in place. Problem is, those bands wear out very quickly, or fall off and get lost even easier. That, and you'd have to have at least a dozen of 'em to hold the hose well enough to keep it from 'squirming' off of the support.
Its ironic - its a case where a 'law' in some places put in place to prevent a mess, creates the risk of creating an even BIGGER mess, as it did with us once. :)
Anyway, we leave the hose connected up when we have a sewer connection, to allow for easy dumping of the gray tank every few days (with a family of 4 and all like to take a shower every day, gray tank fills up fast, haha!). Rarely use the hose support for the reason described above, and its never been a problem. I just have to remember after dumping, to pick the hose up to let it drain out. Takes just 5 extra seconds, and much easier than dealing with the mess that happend the day the hose popped off on me! And, no, I've never had the hose come off from where it goes into the sewer outlet when doing that. Thats why you put weights of some kind on that end, to prevent that from happening.
I do like the idea some have discussed, of using a few sections of gutter to support the hose. I think a gutter would be 'deep' enough, that the hose could not squirm out like it does on the slinky support. Not sure that PVC pipe, or the contraption CW sells mentioned previously would prevent that from happening.
One of these days, I may just go buy me a few sections of gutter from Lowe's, and build me a support that can be used without risking the hose falling off and causing a bigger problem. :)
On a separate note: Why is it that any thread on the subject of sewer/'poop', gets sooo much attention here from everyone? 6 pages of posts already, in just 3 days. :)