Yeah, another dog will definitely wear her out more.
Or get one of those electric ball launchers lol really worth it I'm sure.
Or you should look into a flirt pole. Supposedly it's like an hour walk in 10 mins. Not sure how true that is but it is a lot of exercise cause they jump and chase it and stuff (if they want ha). And you stand still besides moving it 
 
I got one for Gator but he's lazy (or smart?) and waits for it to come to him and the only way he chases it is if I run around and make it move a ton which defeats the purpose lol
But they use them for pits and other real energetic dogs
This is the one I got. They have different sizes and types of lures. This particular one is also mow on Chewy.com and Amazon.
http://www.squishyfacestudio.com/flirt-pole-v2/
Supposedly it works wonders lol
Also, they say mental exercise/stimulation is extremely important and as important as physical exercise so you could try getting her some of those puzzle toys, teaching her some tricks or even practicing obedience, playing some scent games, etc. Might help tire her out some with less physical exercise.
Also I've heard backpacks can help a lot. Idk why exactly but it makes them think they have a job to do which can tire them out? Put one on her, empty at first of course, and she can wear it when she goes outside or whatever, and then eventually you can add some weight. Maybe some water bottles or something. For some reason having the job can help and I even heard of one dog that refused to go outside without her pack on lol
And also a tennis racquet oddly works for hitting the ball too. My dad used to use one for our old lab because he was obsessed and would make your arm fall off lol so he would take the racquet and hit the ball all the way across the yard (our yard is huge), obviously way further than your arm can throw it, and they get more exercise. Might be worth a try because them you can get more exercise in with less throws/hits if you have a big enough area to do it in haha
Anyway, I know all this stuff is still work and time consuming, but it might be at least a little bit easier than having to do all the physical exercise. If you like it though, biking with dogs can truly help too, they seem to like it.
What kind of dog is she?