>>368095204
put 1 on your chest. the other two can be put on either your elbows OR your knees, but obviously not both since you don't have that many. 
I'm in the same situation, but I end up using just the chest tracker and no elbows/knees. sure it's a "waste" of the 2 trackers, but the gains are very minimal and it's a hassle to deal with.
if your vive trackers are 2.0's, their battery life probably won't last as long as your tundras. in that case you could consider having just a chest tracker, and then hotswapping it out with another tracker when it gets empty.