I'm not sure if there is any way to decrease The weight on your face.. Trust me.. I was on my highest dose in high school so I searched high and low for methods. The only thing that was close enough to work was make up tutorials to give the appearance of a slimmer face :)
As far as the body weight gain .. I tried to eat less salt to prevent more bloating than normal. I know how difficult it is since you feel like you want to eat everything inside the fridge.. Sometimes maybe even including the fridge! Take care of yourself and hopefully your blood will tell your doctor "hey, I don't need so much prednisone anymore! Get it out of here!" and then hopefully you can taper :)
Just wait it out! I know there are plenty of doctors who don't want their patients on steroids for too long

With lupus you will gain weight and then you'll lose it so it will vary as time go on, so keep all your fat and skinny clothes you'll go back and forth as time go on.....😏it's a long ride.......i've been diagnosed for over 20 years now i was at my high 198lbs now i'm at 150 so keep your clothes.

Don't think there's much you can do about the face bloating as that's the medication itself. Does anyone get hunger pains? When I'm on high doses of prednisone my appetite is out of control and when I feel hungry even though I know I'm not I get these pains that won't subside until I give in and eat. And it's like this constant nagging feeling in my stomach to eat. As far as exercising try yoga. helps me feel less stiff and puts a bit of energy back into me which is awesome.

Be very careful about your sodium intake and if it helps after a few years use my facial puffiness lessened on its own. If my dose goes way up during a flare up I do have some puffiness again for a period of time.

I am sorry, Mrs_Amanda, Prednisone can be very helpful, but the horrible side effects, such as weight gain, are just part of the package.
Try to exercise, as JanetYounglove recommended. but make sure that you don't over-exert yourself. That would make the Lupus symptoms even worse. Listen to your body, and stop exercising when it tells you so...