This could get into a checklist I suppose of what you need, and there are plenty of check lists out there, but to keep it short, your starter kit should have:
1. sewer hose.
2. disposable gloves and disinfectant wipes for above.
3. drain elbow (depending on what kind of dump stations you have in your area).
4. white potable or RV hose (they don't smell the water like a regular garden hose).
5. pressure regulator (some campgrounds can damage your water system).
6. water filter.
8. chemical treatment for black holding tank.
9. surge suppressor
10. voltmeter (if your surge suppressor does not have an automatic disconnect).
11. spirit level (to assist leveling, especially if you have slide outs).
12. Wheel chock.
At least that is my minimum starter kit. Some may seem as unneeded, but you will soon run across needing every one of them.
One issue I have with a Rhino-flex (and I own one), is the can be harder to put on and remove. It's hard to get good access to the sewer fitting in our coach due to it's location, so I can't get a good grip on the twist ring, especially with sanitary gloves on.
This is partly due to the design of the Rhino-flex fitting as the major part of the body rotates, and partly because my sewer fitting is low to the ground and tucked in under the coach chassis, and I can't get both hands on it.
In contrast, the fitting on the cheaper ones do not rotate, which can give you a better grip when you don't have adequate access to the fitting.
After using the Rhino-flex, I bought one of these sewer hose wrenches, which makes it a lot easier to install and remove (especially when wearing gloves):
A strap-wrench works well too - although it does take some time to put it on, and a bit more difficult when wearing gloves.
Of course, over time, you will likely be wanting to add a few tools, a spare parts kit (fuses, light bulbs, and things you seem to break often), tire gauge, and so on.