The best way of course is to get a humidity controller with both a humidifier and dehumidifier plugged in. Since you don't have access to these items you gotta do it the ghetto way which actually still works I used to do it all the time back in the day. We have desert winds in the fall in California the humidity sometimes gets like you under 15% extremely dry. I would hang and dry my plants in my grow tent so on the extra dry days just toss a few wet towels down on the floor. That simple. The air inside the tent is super dry so you can zip it up tight and then all you need is a tiny little desk fan set on low so you can move around the air a bit. By tossing a few wet towels on the floor inside the drying space it automatically starts raising the humidity due to the evaporating water. Once the towels start to dry out you just moisten them agin. This isn't perfect like i said kind of ghetto but it gets the job done. With 10% humidity it would usually zap your flowers in a few days but with the wet towels it will slow down that process so hopefully you can stretch the dry out to a week or more. Longer and slower is better you don't want to zap them fast they will hit way harsh and burn your throat. As far as the temperature I would choose the coolest room in your house. A basement would be good. Basically anywhere that is less hot than the other areas. Good luck!
When it’s very low humidity, I hang the plants and then put a “curtain” of plastic around them.
A large garbage bag works as long as there is some air flow.
Instead of directly into jars, I use plastic tubs with a large slot cut in the lid.
Using a hygrometer, I open it close the slot with tape to keep the humidity steadily dropping.
The buds will handle RH of up to 98 as long as there is air exchange.
The whole idea of burping jars is to give fresh air and lose moisture, but rather than start and stop, a slot allows a steady process.
I try to never let the buds get crispy dry on the surface, yet keep a slow steady evaporation happening.
If you are in a zero RH environment, you can seal them off and keep the micro environment where you need it. Just be sure that no moisture ever forms inside the bag or you’ll get nasty things growing.