I have a bunch of random fruits in my frig ... An Apple some orange peals few grapes lemon .... Think it would be ok to just toss it all together for a gal mix?
I did, the worst that can happen is it won't taste good, but often the fridge/freezer clean out wines can be good to great. Since you have the fruit it doesn't cost much and won't take much time to make a gallon batch. Go for it.
I've done it a few times one of my best wines that all my friends and family love came from a clean out wine. The worst that can happen is it taste like crap.
When I do a clean out I go off my hydrometer reading with the sugar. The tannin depends i would add a little since you are putting since you are not making a full grape wine. But I'm still kinda new to the wine aspect as well.