The only reason an MLP investor holding in an IRA has to file is if the total UBTI in the account that year exceeds $1k. And the UBTI form is filed by the brokerage, and NOT by the individual investor. Other than that, you never file anything, and can just toss the K-1s in the drawer. There is nothing to file when you sell inside the IRA.
Given that KMP has not declared any UBTI for at least a decade, it isn't likely you will hit the $1k tripwire with KMP.
All that said, KMR (the i-share near twin sister of KMP) was designed for IRAs and similar accounts (like mutual funds). KMR can never generate UBTI. By paying a dividend directly in the form of new shares, you are automatically reinvesting anyway...which you would likely be doing in an IRA anyway.
I own KMR in an IRA, but also other MLPs. I keep an eye on my total UBTI...it isn't hard to keep under the $1k level, but KMR makes it that much easier.
My broker checked with TWO different accountants and said the same thing. I then asked my accountant of 35 years the same thing. He concurred. This applies to a 401k and the IRA. You will recieve a form in the mail and you give it to your tax preparer and forget about it.