We have an '05 Rockwood 5th Wheel we plan to live in for a year.  When we bought it we had our existing agent provide an insurance policy but we're not happy with it as it doesn't seem very RV specific.

There are RV Full Timer's policies.  Ours is through National Interstate, and we us an agent  in our state of domicile to find policies suitable for our situation. Our agent specializes in fulltimer insurance.  I don't know if she works outside of SD.  But generally you will find more such policies in states that are full time RVer friendly.

Your caveat that you (only?) intend to do this for one year is the gotcha.
I am in the same boat as you with too many balls in the air to commit yet.

When I looked into it in March I found that while there *are* ways to get better coverage... to do so (without exorbitant cost) requires changing many other things about legal status. In particular residency as many states insurance rules simply don't have provision for real fulltimer policies. Your state might though so be sure to ask locally too.

A kludge is to have your old (or a beater) car parked at your 'rents house with minimum collision insurance and "assert" that the family home is "owned"... all to get you that combined asset status that underwriters look for.

Doing the residency change will affect still other things (like taxes and their costs) and it soon becomes like the analogy of squeezing the balloon. Action and re-action. And that is dependent on tax bracket and nature of income.

Retired people who have investments but little in earned income have a very different set of concerns compared to working age people with mostly earned income.

The business aspect only complicates this more.

Wish I had more/better news for you.

Uh oh! This is something that I've not yet explored. What exactly are the pitfalls that I should be aware of? I want to be sure my rig is covered tongue to tail. 

We're Texas residents via Escapees, and have a full-timers policy through an Escapees endorsed agent. The policy is through Progressive. One of the bennies is that it covers us for stated value of the rig, meaning, what we paid for it. Always. So if it's totalled, we would get what we paid for it in 2007, not what it's worth today. And that's good for the life of the policy. There are very few policies like that. I suggest calling them, even if you're not an Escapees member.

I think what insurance companies are looking for are people running businesses that would involve the public going in and out of their rig. i.e, a mobile pet groomer, dentist, hairdresser.

As Internet-based professionals who don't have public traffic coming in and out of their rig, you would most likely be fine. The insurance that we had for home based business was exactly like that. As long as we didn't have an "Open for Business" sign (literally) on the door, we were covered.  The way we run our business out of the RV is exactly the same.