Again, a 32 in a 35 is nothing to care about ir think twice about.
With that said yet again, i do think there is a limit at which using smaller diameter tubes no longer makes sense.
I have used smaller diameter tubes in large tires and i think they arent as durable or long lasting. Total guess, but i think its because the tube is stretched thinner than it was intended.
A 40mm tire has about 215% more volume than a 23mm tire. 100% more is twice as much volume, and this is 215% more. Yes, we can talk how few millimeters difference the tires are. Volume difference though?...what a tube is made to do (fill space), is significantly different.
I am shocked (but i guess not really) that this has continued so long.
Its really surprising to see anyone argue my original point of- the op's situation will work, however there are limits.