What is the easiest way to apply for the LTR wealthy pension visa in Thailand?

I would say that it depends on how you plan to qualify for the $80,000/yr passive income. Do you have pension income that meets that amount? or are you going to propose some other types of income as passive.

If you have pension income of $80,000/yr then assume that it will take at least one month to process your application. If you are planning to use other sources of income as passive income then you may have a lot of discussion about your income sources that could take a considerable amount of time. The same issue applies to the insurance you plan to use to meet the insurance requirements. You would think 90 days would be enough but it will depend on how simple your finances and insurance are.

When I applied I had pension income that qualified and I had a thai insurance policy already. My application was as simple as it gets.

I've read accounts of people getting it done in less than a month and others that just gave up because they couldn't meet the requirements when they originally thought they could.