There are a few hotels with connecting rooms. Pullman has one, it's 80,000 baht for 2 rooms. I know they're designed to facilitate families, I don't know if they'll allow 2 people (friends or otherwise) to use the adjoining rooms. Can't hurt to ask though.
So the Non-OA does NOT require 800,000 baht in a Thai bank account like the OA does. SOME embassies may require proof of finances in their home countries currency equivalent to 800,000 baht, but in my experience this varies by embassy. I should have clarified though I meant the 800k in a thai account for 2 months.
I was just writing an article about this too. Non-O is a single entry visa good for 90 days that can be extended for 1 year in the country. The extension requires 800k baht in a Thai bank account for 2 months before you apply.
A Non-OA can only be obtained from the Thai embassy in your home country, but is a multiple entry and good for 1 year. You do not need to put 800k baht in a Thai bank account, but you do need health insurance from the Thai Immigrations approved vendors.
Insurance is only required for a Non-OA, which can only be obtained in your home country. A Non-O based on retirement does not require health insurance.
Sorry, I'm not sure what a MOT is. The vehicle needs to be inspect, but they do that at the DLT when you transfer ownership. Proof of tax payment is in your bluebook. it documents the owner and tax. Insurance is a separate paper, and the government sells their basic level coverage at the DLT, or you can shop around for a 3rd party insurance company.
Make sure you get the green book, bill of sale, and a signed copy of the sellers ID card. You'll need a certificate of residency and your passport. Take those documents to the DLT to transfer the greenbook into your name. Tax and insurance is paid for there too.