A viewer on my youtube channel told me you could make flame retardant with borax and spray it on your tent . He suggested I do a google search on it to come up with the formula and so I did. There are many possible pages to read that came up as a result of the search.
I clicked on a few and came up with this, among many other similar formulas:
Homemade Flame Retardant
For a make-it yourself fire retardant mixture, mix 7 oz. Borax, 3 oz. boric acid, and 2 qts. warm water. Stir to dissolve completely. Either dip the fabric in the mixture or spray on to thoroughly saturate the material until it drips. This product will wash right out without damage to the fabrics so if you have to use a bedsheet for stage curtains, it won't damage them for at home use.from the website:
I don't know, though, if the rain would wash the product off the tent. I imagine in time, it would and you'd want to reapply the spray.
If anyone tries it, please let me know. Once I get my car out of the storage container here at Man Camp in Yellowstone, I'll get the stuff and see what happens. Stay tuned for a full report this summer.
May all your trails be lighter.