Given that holding points can't be banked, your UY benefit is actually not 8 months, it's more like 8 months plus 30-32 days.
Say you have a December UY. Your banking window closes July 31. But if you book July 1-7, your ability to bank those points due to cancellation is actually going to be May 31, or so. After that date, even though you are within your banking period, you are within 30 days of arrival and your points will go into holding regardless of your banking window.
To maximize your UY-based insurance, you need to go back 8 months from your last date window of travel and can add 30 days.
If you normally travel June 1, you may want to open up your UY options to September or October. With a September UY, for example, your last day to bank would be April 30th which is just before your 30 day holding window. If you consistently travel mid/late June, an October UY would allow you to bank until May 30th which would cover your pre-holding window.
All this is to say you may be able open up your UY shopping options. Rather than looking for only the perfect December UY contract, you may find an even better September or October contracts worth considering.
And all that said, who knows how you'll eventually end up traveling in 25plus years. But that's based on the best information we have now.