If you're forced to stand in a line, and people with guns are making no secret of the fact that they will beat you to death or shoot you if you get out of that line, and you can see that they've got a donkey at the head of the line lined up to kick the next in line in the crotch, but then you get to the head of the line and they just have some guy give you a stiff right cross to the jaw... did you get a benefit?
The verbiage you used in your OP makes me think that in that situation, yes, you'd think that getting your teeth loosened is somehow a benefit to you.
The best thing that you can do in this situation is stop trying to convince other people of an idea until you understand the idea fully. The idea - no, it's not an idea, it's a cold, hard fact - is that the state is at best useless to you. In most circumstances it simply takes your resources and shoves you around and then offers you NO BENEFIT WHATSOEVER. In those rare cases where you can point to something that actually is a benefit, we can pretty quickly show that the amount of money, time, and headache you spend to get that benefit is way in excess of what it's actually worth.
But let's go through this list in detail and hopefully you can see that there isn't a single "benefit" on this list that isn't easily solveable through libertarian ideals.
1) Immigration benefits: simple, stop telling people where they can and can't go. Enforce private property rights, but otherwise recognize that there is no rational reason to keep brown people out of the country.
2) File income taxes jointly: Why the fuck is everyone so in love with income taxes? Get rid of them. Problem solved.
3) Joint parenting rights, such as access to children's school records: Eliminate public schools. This is the most urgent of all libertarian positions. It would be nice if we all recognized it.
4) Next-of-kin status for emergency medical decisions: let's call this what it is. Authorization to euthanize. What other medical decisions are we talking about? What other medical decisions can't be made by the person in question? Does anyone else think it's a little strange that gay people are really just looking for the right to kill each other?
5) Family visitation rights: Prison? Easy, get rid of prisons. Yes, I'm serious. Hospital? Ok they have a point on that one, but let's privatize hospitals first and then talk scenarios.
6) Custodial rights to children: I don't understand this. Gay people don't breed. If they do then they had sex with someone of the opposite sex, and that person has custodial right because that person is a parent. Are they saying that a lesbian should be able to get pregnant and have a kid and then her gay lover should get custody but the father should not? Nuts to that!
Maybe they're getting artificially inseminated? In that case, why don't they use existing paperwork to establish legal guardianship of the partner? How was that not already possible?
If that was substantially more difficult than a marriage license, then sure, I see the point - but the thing to focus on is that the government was making life difficult, not that it was making it less difficult for other people.
Custodial rights of shared property: I'm not sure what the problem is here... I can share property with my mother or neighbor and we both have custodial right, so what was the problem here?
Child support and alimony: Get rid of those programs. Problem solved. Yes, I'm serious.
7) Qualify for domestic violence intervention: Ok, wait.... so you can't wait to get married to the guy who's beating you up, and afterward you want the cops to do something about it?
Of course this is totally solved by treating "domestic violence" as just regular plain old violence. There's no more reason to treat "domestic violence" as something special than there is reason to treat hate crimes specially.
So the answer again is "Stop having the state do that".
8) Receive spousal funeral and bereavement leave: this is between workers and employers. What's really being said here is "we can now force businesses to do something". That something costs money, and that money doesn't go to the employees.
9) Inherit property: the word "inherit" by definition includes a predecessor and a successor. We're not talking about gay couples when we use the word "inherit", we're talking about sons and daughters. There's already a facility for that, and joint property ownership covers up other issues gay couples could have complained about.
Is there an issue with being joint owners of property? Or are you just not putting your gay lover's name on the deed, and expecting other people to figure it out for you?
10) Receive spousal benefits when officer is.... stop right there, eliminate the constabulary. That's probably the second most urgent libertarian issue.
11) Receive spousal SS benef... eliminate Social Security.
12) Immunity from testifying against spouse: I'd need to type up several pages on this for our statist friends here, but if you're really anti-state, the idea of threatening someone with prison if they don't help you put someone else in prison doesn't have to be explained a whole lot.
13) Apply for housing assistance if in a low-income family: Can you guess what the answer is?
14) Apply for copyright renewal: eliminate intellectual property laws.
15) Receive spousal recognition for policies at Arlington National Cemetery: Eliminate the standing army and for the love of God, stop the dead ancestor worship, stop the state religion involving soldiers, and above all stop killing off young men and claiming it's a good thing.
