I'll share a tip that I learned from experience: do not turn or twist any screws on the engine unless you know what the screw does and you know what you're doing. On an engine, turning a screw 1 quarter turn and then returning the screw to it original position may not return the setting to its original position.
Alternators are rated at a higher engine RPM than idle, usually 2000 RPM. In other words, an 80 amp alternator puts out 80 amps if it is full-fielded at 2000 RPM.
One of the reasons that emergency vehicles like police cars have such huge alternators, like 180 amps, is to power stuff like emergency lights during long idling periods.
If you want to run big loads like air cleaners, spot lights, map lights, computers, 2 meter radios, etc., you will need a big alternator, and to power a big alternator, you need a big engine, and if you get that big engine, the fuel economy will be nowhere near as good as you are getting now.
The Sequoia is available with a 115 volt outlet to power your air purifier,
4WD to get you through the snowy ruts, and a big alternator (IIRC, 120 or 130 amps). It has built-in map lights and has in-dash navigation available. It will handle all sorts of extra gadgets while handling snowy roads (or even no roads) with ease. On the negative side, the gas mileage is roughly half of what your Corolla gets.You can get a Ford Crown Victoria with option package P71 that will handle big electrical loads for less money than the Sequoia, plus there are probably dozens of supplies of spot lights and map lights! My guess is that fuel mileage will be the same or slightly better than the Sequoia.