I'll try to add something by taking into account your comments to the other answers.
Do I get down to their level of insults and point out their every flaw
to attempt to earn respect?
Definitely don't do this. It is still somewhat uncertain to what extent they are being friendly but rude versus outright disrespectful. If they are just being buttheads, you will immediately set a combative tone. If they are truly being misogynist, you are attacking their professional weaknesses, which will likely backfire. Besides them becoming defensive and putting you further on the outside, they have 15 years of experience to throw back at you.
Not to mention that they do derail my legitimate work meetings and
serious complaints with these comments and sometimes do it in front of
people from outside the department.
What are the nature of the meetings and complaints, and who are the outsiders? Sometimes newbies can be overzealous, and a team "casualizing" these events is just a reflection of the importance of the issue to the company. That said, they could also be heavily disrespecting you and actively parking the bus on top of you. It really depends on the specifics, but they're really begging for a lawsuit like that.
How can I handle this without making myself even more of an outsider?
First, decide if you really want to be an insider. Are these generally likeable people with whom you want to work? Assuming they aren't rampant sexists, a likely explanation is that they are just trying to vet you. They want to know who they're working with and whether they fit in. The fact that you're a woman and relatively inexperienced are what make you different. Noticeable differences are the most obvious candidates for why someone may not fit in with a certain social group, and naturally the first things to be scrutinized.
From mhwombat's answer:
- Look at what the guys on the team do when they are fed up with someone else's behaviour, and consider doing the same.
- Tell some anti-male jokes.
Emulate your colleagues' approaches to interpersonal conflict and matters of professional respect. This is a universal thing, not tied strictly to gender, race, or even humans. Try to map out the escalation of conflicts with regards to volume, directness, negativity (or lack thereof), and sarcasm/humor used in communications, then try to see where you fit.
If they engage in back-and-forth razzing with each other, match the tempo and duration. For example, if it's "Poke," "Zing," chuckle chuckle, follow suit. If you zing someone back and they try to keep at you, admonish or deflect based on the social norms. Enforcing the social rules correctly and appropriately shows you understand them and care about them, making you more welcome.
Two final points:
This is advice on how to fit in. Remember, you don't have to fit in. You will do your best work and be happiest in a place already aligned with most of your values, where you can be yourself, and where who you are is accepted and valued. Find that place and worry about fitting in there; everything else is a temporary solution at best.
Women are better at emotional communication than men. Women in general are better at detecting and transmitting emotional content. Men, being less sensitive to emotions, can be unaware of the emotional subtext they are sending. Women are likely to hear it, even though it can be unintentional, misconstrued, or outright false. Women are capable of expressing a linguistic and emotional message at the same time, while men will only perceive the linguistic message and any overlap.
For you, this means that despite 8 months of torture, they might genuinely still think it's playful ribbing that you are graciously accepting. Many groups have a "Milhouse," a submissive member who is the butt of many jokes, teased relentlessly, but a beloved and (secretly) respected member nonetheless.
You don't have to be a "Milhouse," and you have a social and personal imperative to not be a "skirt." Stand up for yourself, command respect, but keep in mind that your gender and experience may simply be topics and not the cause.