@Anthony454
You can set different min nights for specific periods (but not for max) - so the way around it would be to increase the nightly rates for July and August.
With a 10% weekly discount, if you charge $20 per night then $20 x 7 with a 10% weekly discount is $126 but a nightly rate of $30 x 7 with a 10% weekly discount is $189. - Not sure what you mean by "discounts override normal nightly, weekly, monthly prices". The discount is applied to your nightly rates and you can adjust the rate of each night separately.
Also for certain periods, for instance from January~May, if you want to have a longer min stay than compared to July~August it is possible to have a 5 night min (or even a 28 night min if you wanted) for Jan~May and a 1 night min for July ~Aug.
I suggest you familiarize yourself with the functions available in Pricing >Length of stay discounts and Availability >Trip Length > Additional requirements under Calendar. Change the settings then go back to your listing calendar as if you were a guest and try putting in different dates, no. of guests etc to play around with it to see how the rules are applied.