Weight pull is great, lure coursing is also fantastic, I have justed started that with my girl phoenix (see my signature) she loves it!
Also for excercise you can get a flirt pole and use that in the backyard, good for building muscle and stamina as well as tiring out your dog.
Does Topaz like water? Swimming is great 5 minutes of swimming equals about the same as 30 minutes of walking.
Your girl is gorgeous!! Congrats.