Either change oil and filter at 12,000 miles
Or change oil and filter at 12,000 miles and change oil at 6,000
I too have a car with a hard-to-reach oil filter and routinely go for the latter, changing filter very 24k km and oil every 12k km.
Rationale: in almost all cars oil pump is volumetric, gear type. This means that the amount of oil reaching engine internals is NOT influenced by how dirty the filter is. Only the "effort" made by the pump to push oil thru it changes (and a bypass valve saves engine and pump in case of excess pressure) so you know that your engine will be having the oil flow it need. Moreover, in a perfectly working engine the amount of dirt "caught or trapped" by the filter is very low anyway and little influenced by the driving style. So no big deal in running it for the "full term" specified by manufacturer.
Oil, on the other hand, really gets "trashed" by older engines and sport driving (higher piston blowby) so there is a clear advantage in changing it more often.
If you want to go "full science" on it you can install a differential pressure sensor across your filter and send you oil to a lab every ~3k km and find out what its wear pattern is.
Personal experience: after 12k km of hard driving the oil from my W10 engine smells like gasoline and has lost (empirically tested) viscosity in a noticeable way. After 16k km the wear is so bad that after replacing it the engine sounds different (not unexpected on that engine).