You probably don't want to do too much pulling if your dog is not grown. They should really have a harness made for pulling. I would check ebay or dog forums for a used one. I don't want to pay a lot either so the few times my dog pulled I just borrowed one that fit him.
Liesje & the K9s
Nikon (GSD) U-CH SG SchH1 KKL T1 FO PA TFE-I FDCh-S CL1-R UJJ U-CA HIT TT CGC, free reign semi-retiree
Coke (All-American), couch warmer extraordinaire
Indy (All-American), flyball star in training
Rainbow Bridge Kenya (GSD) U-CH FO OB1 CL1-R CL1-F RA HIT TDI TT CGC