This seems to be very related to the SCS thread, but I will bite.
China really needs to settle its dispute with its neighbours if it wants to keep its trade routes safe. I was reading today on some of the articles about those "man made islands" in South China Sea
The way I look at is that China has probably angered some of its neighbours by claiming islands/reefs that are far from its border. They have different disputes with different countries. In some cases, I think the disputes are so large (like the one with Vietnam) that I don't think they can be settled. In other cases like Philippines and Indonesia, I don't see why they can't be settled. In the end, the rocks/reefs of South China Sea provide both strategic value and commercial value. China has reclaimed enough land around its reefs to control South China Sea conflict and to successfully conduct electronic warfare against all naval ships passing by. From strategic point of view, I don't think they need to build more. Commercially, they should try to work out on sharing the possible oil/gas fields in these areas. These areas do not hold Saudi Arabia level of reserves. Imo, it's more important to work it out with neighbours rather than each side holding out to claim everything.
If we just go through the countries in this area:
1) Philippines - A rather poor country with a lot of internal problems and several disputed islands with China. China already sells/gifts a bunch of weapons to Philippines. There is a lot of ethnic Chinese people in Philippines that do well. It shouldn't be that difficult for China to work something out and pull the Filippinos into its sphere of influence. The possibility of EDCA seems to be a far greater cost to China than some gas field around Spratleys.
2) Indonesia - I find Indonesia's claim to Natuna Sea to be a little aggressive, since Malaysia is far close to the islands that Indonesia is claiming. Again, Indonesia is very strategic located. A base in Indonesia would be very beneficial to Indonesia. Indonesia also has a very large and growing population. It has a lot of economic issues and a major city sinking issue with Jakarta. There are things that China can offer to Indonesia for closer relationship between the two countries. Even if they don't completely agree on border, there is no reason they can't settle on status quo and work out economic settlement on oil/gas exploration. Keep in mind that China had exported some weapons to Indonesia in the past. As we get to 2030s, Indonesia would be an obvious target export market for FC-31. China can pull Indonesia into its sphere of influence with some level of settlement on territorial claims, greater economic relationship and more military export. I think the benefits of having military base in Indonesia would be greater than any oil/gas field concessions they might need to make.
3) Malaysia - Another country that China has pretty good relationship with. It's not a country that gets advanced Western military hardware. China can be quite competitive here with FC-31. Malaysia also has a huge Chinese population that controls the country's wealth/businesses. There is already a lot of economic ties between the 2 countries. As China develops newer military hardware, this is exactly the type of country it needs to target. I don't think they need a base here, just neutrality in the event of a conflict.
4) Singapore - As I discussed in the Taiwan thread, China has the greatest resource that Singapore needs - han Chinese people. There is nothing that scares Chinese Singapore elites as much as losing the Chinese majority and end up becoming like Malaysia. Singapore tries hard to import ethnically Chinese people from everywhere in Asia. The young Chinese Singaporeans still all speak mandarin. Again, they have a lot of strong western influence due to its increasing role as the finance capital of Asia. However, there is no reason for China to just accept Singapore as a country that will automatically side with the West. As mainlanders continue to immigrate to Singapore, there will continue to be a lot of cultural link there with the mainland. Singapore can be a link between China and the West. And at some point, China will have enough advanced weapons to be able to export to Singapore.
5) Thailand - Another major influential power. A lot of people don't know this but 60% of Thai population are at least partially ethnically Chinese. There is a lot of Chinese tourists that visited Thailand every year pre-COVID. I think it's absolutely natural for China to fight for influences over Thailand. Thailand already imports quite a bit of weapons from China. The two countries have pretty good relationship already. I don't think they need military base in Thailand.
As a whole, I think China should make ASEAN their major sphere of political influence. They will need to work on some of the territorial issues they have with ASEAN countries. Vietnam might be too much of a hurdle. Every other country is quite possible. I think Indonesia is the major one in there. It's the most strategically located and have the largest populations. Indonesians also have major anti-Chinese sentiment due to Chinese Indonesians controlling most of the wealth in their country. But it's also the country I think China should approach the hardest and maybe support Indonesia's bid to be a regional power.
If China can get its relationship with ASEAN worked out, a lot of its SLOC issues will resolve themselves.