you can get named turnout boots. and also boots for mudfever.. that would also stop her knocking,
IF you find she knocks when ridden the old fasion sausage boots works wonders.. BUT (here i get boring and personal)
id put money on the fact shes actually unlevel behind, this would be due to mucscel wastage. the trainer that had her in racing.. is notorius for not letting them down properely. get somebody to walk and trot her up for you. in a couple of months when youve hacked more etc your proberely find she opens up on the back end.
my old tb., i used weights on. (as reccomended by a vet) just wristbands for humans but weighted, to put a bit more effort into the back legs being picked up. NEVER did i use them ridden, they had a habit of slipping!
*shuts up now*