I'm not a tax professional, so it would be impossible for me to give you forward guidance on what portion of LINE distributions are UBTI. Wish I could but I gotta be honest about it.
As an Average Joe, I observe that non-cash hedging losses tend to cancel out any cash earnings on the income statement. So I don't see how you can have unrelated income when you don't have ANY GAAP income. Of course, taxable income is a different story.
LINE will probably tell you they expect next to no UBTI. One year I fully funded my Roth in January only to find out in March that my adjusted income disqualified me from making any contribution. It was hard for me to know before all the numbers were in...once I did know I sure wished I had waited until May to contribute to my Roth. Same thing with LINE. It's hard to know for sure until all the facts are in & once you find out you may very well wish you had made another decision.