Well done, I think it's a learning process for embassy staff as well, as most of them have only processed on fixed requirements, this visa they are making decisions, a very unusual thing for most public service employees
Others have given you advice, so here is one more thing to be aware of. Under some schemes owners cannot be charged for non payment of the annual fees, the body corp has to wait until the unit is sold and outstanding fees are deducted at settlement. If their are a number of non contributing owners in a block, it sometimes means there isnt enough cash in the bank to do essential repairs. Always check the rules of the Block you are buying into
Given that Thailand is moving to E registration prior to entry as announced in the last week, it's sticking out that they will also be looking at misuse of various visas or visa free, so that some travellers will have red flags before they hop off the plane.
I use an app called Tripit, given you have a confirmed onwards ticket just that it's more than 90 day after, I would post an itinerary on my Tripit app show a couple of trips out and into Thai, using online info. Eg 10days to Hanoi. Bus trip to Siem Riep. If you get questioned (in 50 yrs I've been questioned once) tell them it cheaper to buy the tickets in BKK.
All entries are at the discretion of the Thai Immigration Dept. So when you read about foreigners being denied entry, it's often that information has been flagged on their passport computer record. Often Foreign official will advise Thai police that so and so is a bit suspicious and coming your way. That's when immigration have a harder look, at who so and so is. The law is there but only used when needed lots of FIFO workers have used Thailand as a base for years.