The weird requirements are there to satisfy impulses like yours: make sure that we only give welfare to the truly needy, and to make sure that their lives on welfare are not too good. The whole idea of UBI is to replace that with an unconditional transfer of a fixed amount of cash to every person.
If it's a fixed amount per person, people who choose less desirable housing will have more purchasing power for luxuries. I claim that any attempt to counter this effect will quickly devolve into another system of "weird rules," probably subvertible, and certainly with unintended consequences. For example, what if I am cohabiting and want to stop? Do I need to justify to the state that it must now house me and my partner separately at twice the expense? What if I'm faking the separation in order to rent out "my" apartment on the black market and keep living with my partner? What if I'm being abused? What if I'm sick of exurban Iowa and my "grandmother" "needs" me to take care of her in Haight-Ashbury?
The insight of UBI is that the government's attempt to untangle questions like this is doomed to fail, and attempting to do so is an unacceptable degree of interference in private life, so it should not try.
From what you're saying, I'm pretty sure you actually oppose UBI, and just want changes to the existing means-tested, strings-attached welfare system.
In what way is this anyone's business? In a UBI system, you get, say, $600 a month. That's it. It's cash. No one is asking what you're spending it on. If you want to stop living with someone, you just... do it. Like you do currently. Can't manage it? Get a part-time job on the side to pad your wallet enough to do what you want.
Not trying to bash you, but I think you're misunderstanding the basic concept and assuming a level of government attention that isn't part of the equation.
'little else' = TV in your example, so these amount to the same thing
Because the cost of 'bare necessities' varies by region (housing prices in particular), the only way you'll make this work is if there's a government bureaucracy somewhere that looks at market prices and then calculates some formula that gives you exactly the amount of money it takes to buy X amount of housing, food, etc.
But then you can always turn around and bunk with a friend and then spend it all on luxuries and video games, or secretly move someplace cheaper to live and pocket the extra money. So either you allow people to nakedly game the system, or the government is now in the business of monitoring where normal people live.
There is, the government pays cost-of-living adjustments to its own employees on the GS pay schedule. But cost of living stats measure medians. Paying the median would be insufficient for half the population, and "too much" for the other half.
You'd need to tailor this figure per person.
Like, if the rule is you get median housing no matter what zip code you happen to live in, then there's no downside to picking the most expensive zip code in the nation and choosing to get UBI there. OTOH, if you define limits, then government has made some zip codes effectively UBI-free.