Since you've been feeding her live rats, & I assume you don't raise them yourself (-?), I'd recommend getting her fresh stool checked for parasites by a qualified herp vet. It's entirely possible -since she feeds on live rats- that she has picked up internal parasites that are causing her more hunger (sharing meals with worms!) or some discomfort(that also might be evident by her moving around more). It may be nothing but since you asked, this is what I'd do...a fecal check shouldn't cost a lot, and if she needs a treatment, it's easy & not expensive. Congratulations on having a 28 year old snake!

I hope you enjoy her for many more years to come. If for some reason there are no herp vets near you, FYI snakes can be safely de-wormed using Panacur (horse de-wormer).
Also, I favor adding UTH (regulated) & maybe keeping your heat lamp (dimmed as needed) for winter months (ie. use both sources of heat when needed). I don't think the changes will disturb her greatly...I predict she'll adapt just fine. For power outages, you should keep an ice chest or large styro-foam box on hand (the thick kind that frozen food is shipped in). If the power goes out, secure your snake in a snake bag (pillowcases work fine, but don't use your best ones, in case she has to 'go') & keep your BP in the "ice chest" to help keep temperatures stable. If you have a gas hot water heater, fill 1 or 2 large jars with hot water & put them in too...they'll keep it balmy-warm for 8-9 hours. If your hot water heater is electric, you should keep some chemical heat packs on hand...preferably the kind they use when shipping reptiles, for instant & portable heat. (I've been thru a 4 day power outage in winter during an ice storm using these methods- I had 15 snakes at the time, & none got sick or had any problems afterwards.)
About your aspen shavings & UTH:
Do make sure your UTH is regulated by a reliable thermostat...wood shavings are rather combustible, if the UTH were to over-heat. Think safety.