i mean if u use a doujutsu without the body for it,it would have side effects,
but isnt it that it puts a strain on ur chakra that it uses up way too much too fast,which inturn causes the side effects.so in naruto's case were he could potentialy use the foxes chakra would give him the perfect body for the rinningan,which he could get from kohan(nagato's girl).he would be able to use way more tecs to compete on a higher level than he is now.

wat do u guys think?