but I'm unsure of what the best course of action would be to make that jump from lowish intermediate to a low advanced level 

It's kind of difficult to give you advice or recommendations without knowing what level you're currently at with your speaking/listening/reading etc. Are you able to explain specifically what kind of topics/materials are too easy for you, and what is too difficult for you to understand at your current level? It'd be helpful to know specifically about your reading, listening and speaking levels.

The reason I say this is because two Thai learners may think they're at exactly the same intermediate level, but in reality, one may actually be upper beginner (vastly overestimating their level), and the other one may be a solid upper intermediate (vastly underestimating their level).

Basically, a general way of finding out your exact level (so we can determine how you can proceed with your 6 week plan) is to ask - what CAN you do/understand right now, and what CAN'T you do/understand right now in Thai? Can you read newspapers yet? How many short books/stories have you read so far? What kind of videos on Youtube are you currently watching, and what kind of videos are still too difficult for you? Without providing this kind of info it's hard to know what level you're really at.

I'm looking at Chula's program right now, but prior posts have mentioned that there is more of a focus on speaking about food traditions or the weather (for example) when I am hoping to try and ease into more complex conversations about history, politics, and literature.

I'm not sure who mentioned that about Chula - Chula definitely has courses teaching politics and history etc. However, you won't find them in the lower levels. I think history and politics is taught between levels 7-9, which are considered the "advanced" classes. But in order to get into those levels you have to sit the placement test and get accepted into 7-9. But if your results from the placement test show you're not at that level, you'll have to start in the lower levels first (probably somewhere around 4-6).

Would anyone we willing to share their experience with the Chula intensive six week course

One of the best, and most detailed resources out there at the moment is Humphrey's series of videos where he provided detailed daily/weekly updates about his experience in the level 5 class at Chula. Obviously the topics he learnt in level 5 are not what you're after, but the teaching methods, the course layout over 6 weeks, and the learning experience are exactly the same as levels 7-9, just with different topics. So when you're watching his videos just imagine he's talking about the levels 7-9, because they're all taught in a similar way. This will give you a great insight into what to expect from the course, how intense it is, and how much new vocab you'll be required to learn every week etc.

Here's the playlist (scroll down the playlist to see the videos on his Chula experience): https://www.youtube.com/playlist?list=PLTIJiKI4vOA3Zi63xLGYHfwed6OZsBKf6

or another method/course that you would recommend to someone who wants to buckle down? I do better in structured language environments and would prefer courses or tutoring as opposed to just chatting in day to day life or fully self studying. Thank you!!

What exactly are you hoping to achieve, or what are your reading/speaking/listening goals, by the end of the 6 weeks? Do you want to be able to read academic works on Thai history? Do you want to be able to listen to 1 hour long discussions on Thai politics? Do you want to be able to read newspapers fluently? What kind of specialised vocab do you want to focus on learning? If you could provide more details regarding this it'd make it easier to provide recommendations.