I feel I've done enough for a PhD but my supervisor disagrees

This is a really hard problem that is hard to give advice for. If the advice is bad, you will suffer, not the person giving the advice. You know the personalities better than we do. But, as an outsider, it seems like you are being abused. You are giving, but getting little in return at this point.

Fighting with an advisor is seldom a wise choice. But quitting after five years with good productivity seems equally terrible, maybe worse.

For your consideration only, let me suggest a possibility. Work with the graduate advisor on a plan to get you out the door properly. Tell them that you are feeling abused and defeated unjustly and you need to graduate. It is at least partly the responsibility of the institution to assure that you have a clear path. Take their advice to stay an extra semester, but put them on notice that you need funding, either from them or from a proper job elsewhere. Other professors in the department might also be able to apply some pressure if they are approached properly. They can prevail with your advisor even when you can't. Advisors need the support of their peers, generally, and need to be seen as fair in dealing with students. But don't try any of this if your reading of the personalities suggests it would be counterproductive. But you have a right to insist on a fair path and a right to insist that your advisor and the graduate director do their jobs properly.

If you trust that outside professor enough to ask for a letter applying some pressure on the graduate director, it might be useful (or not, depending, again, on personalities). Most especially if they would consider hiring you.

My advice is to write your thesis up and submit it to the committee. If you are going to have an argument about whether your work is sufficient, it will go better for you if you can show that everything is written up. Maybe you still don't win. But the time is not wasted. And it is too loosey goosey to argue about "done enough" when you're not looking at a document.

Personally I think 6 years, several papers is enough. And this guy trying to drive extra experiments, that aren't working, sans funding, in year 6 is being unreasonable.

Write it all up. Dump it on the committee. Involve the department chairman and the grad school. You may still have problems. But I bet if you show some spine, you end up doing none or at least "less" extra experiments.

Good luck.

You simply aren't going to get a PhD without the signatures of your committee. And the rest of your committee will generally give a lot of weight to your advisor's opinion when they decide to sign off or not.

Of course if you quit now both you and your advisor will lose out. As will the department and school because they all invested resources in you and did not get a successful graduate out of it. Plus you have various rights to make a big fight for them via appeals to the administration. All of this gives you some leverage to negotiate what would be acceptable to finish. As with every negotiation, it often starts from what seems like an impossible point, but it's very often possible to find some alternative or some middle point that can work. If experiments are off the table for you, what else can you do to satisfy them? Talk to the entire committee and find out. You could even do this formally at a qualifying exam if you must. But if your advisor is not yet satisfied, you really should offer something more.

If you are not being funded then the last thing you should do is stick around as a full-time student paying out of pocket to hang out in a lab and be someone's research assistant. Your school may have the option of being part-time (which still costs you, but less at least), or taking a leave, where you can work while finishing up. Ideally you should take the qualifying exam, where you basically propose what your final thesis will entail, and then advance to ABD status. Then you can finish up the final agreed-upon tasks on your own time. At least you aren't going into to debt to do it.

As for your plan of publishing journal articles, I can almost guarantee you that you will come across reviewers just as demanding as you advisor. Major revisions could easily entail months of further experiments in the lab, for each paper. You really need to start one or more of them in the process and learn this. It's something you should already be all-too familiar with before you earn a PhD, frankly.