FTG wouldn't even be taxing on him and it'd be more beneficial for him given how intelligent of a fighter Kakashi is. To imply that he cannot use FTG because it's taxing is rather insulting considering he could use multiple Raikiris, Kage Bunshins, and multiple Kamui throughout the War and even his Stamina improved to the point where he could warp away something as large as a Bijuu without Kurama's aid. His Stamina was hardly a crutch at all by the end of the War Arc, so using FTG isn't even a problem in terms of Stamina. The only instances where large amounts of Stamina is required is when warping large objects or many objects all at once. Warping to numerous Kunai was never depicted to consume a large portion of his Stamina.
To be honest, Kakashi w/o the Sharingan would benefit greatly from FTG and since the Sharingan isn't consuming his Stamina, he shouldn't have any problems using FTG.