It would be the same as "see them until loading screen" anyway.
The real blind fun should be the inability to see ally's champions until loading screen and chat disabled until in-game.
If you want team comp, there's normal draft which is made for that very purpose. Blind mode is simply a 5v5 free for all, which should stay that way even in champion selection.
I am sick of role calling and the poor attempts to arrange team under a minute and less which just ends up as meta every game most of the time until later in the nights where the real fun begins, let free for all be free for all. If you want organisation, go for Draft (hopefully Riot opens that on OCE as well).
EDIT: There is teambuilder too, so more reasons to make Blind REAL BLIND.