80 miles freeway commuting?
Save money by taping over panel gaps.
It's usually a bad idea to go under spec, detonation will be bad.
In fact, I've been keeping all fuel receipts for the last year, so i can at least somewhat indicate, that should I run into some kind of engine failure within the warranty period, that it's not been me using out of spec fuel, that caused the failure.
If you can get cheap ethanol, that might be an option to make regular fuel more knock-resistant. If you stick to 5-10vol%, you should be okay with regard to possible fuel system degradation. This will increase your overall fuel consumption, but if you can get the ethanol for close to free, you'll be better off.