Hi. Actually, I had the brilliant idea of taking up hunting just after I had subsequent spinal fusions at the age of 20 and 21 respectively. I am used to dealing with a measure of back pain, which of course is felt more when you are in one place for a good period of time. For me it helps to provide heat to the area if you are sitting on a stand, for example. Toe warmers or those self-sticking back warmers help. Avoiding medication is great, but let's be real, some basic advil can help. Using exercises for your back make the biggest impact as you build up the support muscles. Don't forget your whole core goes into this. Planks, crunches, etc. Half each for your back and stomach. When you wake up is good, before you head out. If you do just a little bit every day it starts to make a difference. Like Healthy Outdoorsman said.
I am all for staying on your spot through the day if that is the best course of action, so casually try to incorporate some stretches as you stand/sit/or still hunt. Also be mindful of how you will drag your deer and put into your truck.
Most of all, be comfy as much as possible. And don't be afraid to tell your doctor that your back pain is interfering with your life. He/she might have good ideas. Mine was crippling, hence the surgeries (I have had a few now). But I can do more at 38 than I could at 20. You may need a referral based upon your insurance to see an orthopedic doctor. I wish you the best!!
And then the moon, like to a silver bow new bent in Heaven