Try another Thai consulate (Vientiane, Phnom Penh, Penang, etc.) for tourist visa and extend (60+30 days). Maybe can play that game until you're 50 then go with non-imm-O based on retirement.
There is a bunch of secure parking near the bridge where you can leave your car for about 120b/day. A lot simpler than bringing your car over if all you're doing is getting a visa then coming back.
Many "official" embassy/consular websites still contain outdated information (the above screen shot for example). 50+ nationalities (including Aussies) can get a 30-day visa-exempt entry by land or air. The 15-day restriction for most by land entry changed to 30 days as of 31-12-2016, but now limited to twice *by land* per calendar year.