30 minutes car ride (with 'vibrations) is about 10km at worst.
Many options are available if you consider.
Walk: at worst 3 hours, maybe longer depending how long you stop at cofffe shops en route to rest.
Bicycle: at worst 2 hours, though the biggest problem might be balancing upright if riding that slowly; alternatively a tricycle so you can sit down while resting.
Ambulance: you can hire a private ambulance to carry you to and from immigration office. They are specifically equipped with air ride suspension to absolutely minimise any vibration, added benefit medical assistance on hand should you need it.
VIP taxi: With a good driver you may not even notice you are moving.
Or use an agent that offers a servicecyou can cope with.
Alternatively if you can create a medical treatment plan to mitigate or alliviate your symptoms a medical DTV might work for you.
Lastly, give your head an 'attitude adjustment ' wobble.
Your choice to use a bus, which is very likely to have vibrations, that exacerbated a pre existing condition, has led to your current situation.
No reason not to comply with the reasonable requirements of Thai immigration.
Again I disagree with your interpretation. For any embassy to accept learning Thai for DTV it must be within the official catchment criteria, unless you are suggesting the embassy's that do accept are wrong. As is broadly seen Thai Embassies seem to apply individual policies some of which are more current than others, just as some IO's apply more stringent examinations on entry than others.
' filling in a missing part in the Thai visa schemes' is an evolution of those schemes.
I disagree with your interpretation which to me appears not to reflect the evolution of the Thai visa schemes. The use of DTV instead of ED visa is just part of that evolution.
You infer learning Thai in Thailand is not a valid purpose of stay contrary to that specific criteria being allowed under the DTV and being accepted by various Thai Embassies across the world?
How is finding a criteria that fits your circumstances ' tricking the system' ?
The 'system' evolves and changes over time, as folk are now finding with extending the DTV even immigration offices are not sure what to do so an equivalent of the 'border bounce' is easier.