1-The bijuu were exhausted back then:
since their chakra was used by Naruto (usage of yang kurama throughout the war) Obito (creating the holy tree) Madara (Casting the huge scale genjutsu mugen tsukiyomi and trapping almost every being on the planet inside his mukton jutsu) and Kaguya( Dimension jumping, creating a huge TSB)
Nope.
1. Naruto has his own separate pieces of their chakra that he uses. Has nothing to do with the 8 full beasts that are not inside of him.
2. Obito making the Shinju doesn't drain their power.
3. Madara casting IT doesn't drain their power.
4. Kaguya used the chakra of the IT victims, and her own.
The Bijuu were at full power when he used them. All you can prove is that he didn't use all of it, but he still used a lot, and there is no evidence he can replicate that on his own. What he uses when he uses Susanoo is his cap. He can't just add as much chakra as he wants. Not how it works. His Rinnegan summons are trash in comparison to the Bijuu. Using them will never let him reach their level if it even powers his Susanoo up at all.