Hmmm, interesting, see there are many extraneous variables that we dont know or kishi has overlooked or naruto has overlooked
1.R-S can be controlled by clones, this is shown when naruto fired up 2 of them against kakuzu and made kakuzu think the 3 clones had a real one when the real naruto was behind him, this shows clones CAN hold, and USE R-S
This is why im finding it strange that tsunade made it forbidden, last i knew physical damage isnt put into the body once the shadow clones dissapear, in theory naruto can R-S with clones and the damage done to the clones doesnt matter.
2.Why does naruto HAVE to be in sage mode to THROW this rasengan?
See again, i cant think of why sage mode helps it become a mobiel long range attack, maybe he doesnt have to be in sage mode...maybe he does, who knows.
However we know he cant make more than 4 sage clones (as of now) as pa toad said using over 4 would be dangerous, and he doesnt have enough staff.
As time goes by naruto is obviously going to get stronger, his chakra increases loads.
If he can make sage clones, cool, one problem though, peins "clones" or "puppets" dont blow up in smoke, they can be attacked and still survive and/or brought back to life, but i can see naruto using shadow clones in sage mode against pein.