Contact the embassy and explain your circumstance don't waste your time here. See the haters attack you. The embassy will process you quicker when you explain. Sort it before you return to Thailand
You should know the conditions of your visa and it's obligations. You have 14 days before the date and 7 days after or it's a 2000 bht fine. It's not about whether it's useful or not to report to immagration for your 90 days it's a condition of staying in Thailand. Whether you do it or not is up to you and as such you are fined. Don't do it and see what happens
Just apply for DTV in your country come and go as you like for 5 years 10,000 bht fee. No onward ticket required. It's not that hard if you do your research visa on arrival is outdated for long stays why border bounce. Get up with the times