large batch of ginger ale - questions

I've made a few 1 gallon batches of ginger ale using a ginger bug I cultured from grated organic ginger. I've been able to time bottling/carbing for good result, it was delicious and disappeared too, so I decided to make a larger batch using my beer fermenter. Tasting and bottling was now more complex and I was busy, so I ended up fermenting too long, and now it's more dry/sour than I prefer.

Is there any kind of sugar or natural sweetener that I can add that won't get eaten by the ginger bug (yeast + lactobacteria) to make the timing less critical?

I'd rather not kill the bugs with heat or some chemical, I like the probiotic aspect.

Also, it will take a few weeks to drink all of it, and I don't have space to store in my fridge. I tried to practice same level of sanitation as with beer, but could there be problems with storing out of the fridge?

If those bugs work like the beer yeast, lactose might be a good alternative to consider due to its unfermentability.

Good luck.

Lactobacteria like lactose

cider folks can have the same issue(ie adding a nonfermentable sugar), so you can check out that part of the forum. Remedies I've seen range from stevia to xylitol.
Do you plan on bottling? I would think that leaving it in a bucket or carboy while you're drawing samples out over a period of several weeks-month might lead to contamination problems.
oops, sorry. Just saw that your original post was back in June. How did things turn out?

I'm bottling. My previous batch fermented quite warm, and turned out quite tart, but no problems sitting around in a bottle for a couple of months. It was nice but better mixed with a splash of lemonade. Latest batch fermented for the same time but cooler, and a few days after bottling still has some sweetness (but less carbonation).

I'll check out the cider forum. Perhaps they also have tips on calculating alcohol levels when there's bacteria involved