I first looked for longer clutch cables for the XR600 and there were none listed so I checked for the XR650l which is basically the same and they list the +3" cable.
Removing the dip stick while the engine is running is possible. There will be some oil spitting but nothing to terrible.
Steve in SF
87 Harley FXRS-SP ~ 06 KTM 625 SMC ~ 72 Honda CB750/915cc ~ 92 XR600/654cc ~ 95 XR650l/675cc ~ 03 CRF450r ~ 05 CRF450x ~ 02 XR650l/675cc ~ 86 YZ490 ~ 93 YZ80 ~ 93 XR650l Project