Udon Joe's comments are spot on
Understand that PR is NOT like a visa application, where you simply provide paperwork to meet the minimum published requirements, pay the actual published fee and your PR is issued.
PR is not just another visa - in fact it’s not even a visa at all.
PR applications are handled and vetted by a special team of high level government officials at Chaeng Wattana government HQ and by high ranking officials across all important Thai ministries in Bangkok. You sir, have got to be Mr perfect.
I will go as far to say that the published PR requirements mislead most potential applicants into believing that they can achieve PR status by one or more methods, whereas in fact, they don't even stand a chance by any published method.
So don't believe the published requirements - the PR team is after way more than that!
If I was to try and put my finger on what the PR team are actually looking for versus the PR application criteria... based on experience, I would say that most of the published requirements represent about 20% of what would satisfy the vetting procedures for all requirements across the board. As for the application fees - well, that’s a laugh. After your own legal and administration costs preparing the myriad of documents needed plus a dozen visits and overnight hotel stays at CW, plus some express processing fees 'cough-cough', you'll easily spend USD10-15K. Maybe more if you need to travel back to your own country to legalize and have apostilles attached to any of the many required documents. The process itself could easily take many years. Issuance of the PR could also take several additional years after all vetting and payments are completed.
Further, your unfortunate lack of Thai partner is not helping matters (extra points for that), You'll need a high paying job(read my 20% rule above), most applicants I met were professionals and spoke decent business Thai (no requirement mentioned on the application form), most had a lawyer or CPA helping with paperwork prep etc, etc, etc.
I hope this information helps - FYI, I was issued PR 3 years ago. I now attend Thai government school as a regular student(PR and my name in a Thai house blue book permits me to do that) and have just completed M3 Junior high school education and national curiculum exams.