There’s no need to weigh snakes!
If you’re using a UTH and a CHE that should be plenty of heat. I only use one heat source (RHP, CHE, or UTH) on each enclosure. A 4x2 isn’t that difficult to heat. I think your basking temps are a bit high at 92-98. I don’t keep any hot or basking spot over 90. As long as your snake has access to a warm spot the cool side temps shouldn’t cause any issues. My typical winter temp gradient is 72/84 with a natural nighttime drop to about 68/78. I keep boas, colubrids, and pythons in these same conditions.
As far as feeding goes it’s totally up to you on how to deal with her. I take an eat or starve approach with any healthy animal in my care. They might resist for months, or even a year, but my experience has shown that the hunger ALWAYS wins in the end. There’s really no need for a battle of attrition at this point though. If you’re already scenting the rats then go ahead and give her the mouse too. I have a carpet python that does the same thing. He doesn’t want to eat medium rats by themselves but he’ll take them when I thaw them out with mice. I usually give him the rats and give the mice to my other snakes as snacks. This last feeding I gave him both prey items. If I starve him for a month or two he’ll eat an unscented rat, then he’ll refuse the next one, and we start the process all over. I’ve learned that it’s no big deal if a small or medium sized snake stays on mice. At most you’ll just have to feed 2 mice per feeding instead of feeding one rat when they’re adults. I refuse to consistently feed them more than two prey items. For young BPs just feed the most mature prey item the snake can handle.
Lastly, even with just one snake, and with the average $30 flat shipping fee most online suppliers charge, it’s still cheaper than most pet store prices.