Dlago
The best that can be done after defining the problem is to go for max fidelity (which you are already doing). If you are looking for a setting/option, that can help you force the solver to use the remaining memory, I am afraid that doesnt seem possible.
I understand that with the available memory, there can be an urge to use a better resolution and increase the efficiency further. But unfortunately as I said earlier, the trade off is to ensure "No Crash" and remain conservative.
Regards,
Gaurav