Making 5mans vs 1v1v1v1v1 "fair" will never actually be fair for the solo queuers.

The main advantage of the 5-man in this situation is their coordination, which they will use to absolutely DESTROY some of the solo queuers. Do you think the solo queue player is going to enjoy that game when he's 0/3 at 4 minutes and getting tower dove by 3 people to take him out of the game? Because that is exactly how you take advantage of the coordination and voice chat advantage. You take people out of the game. Then you hope you will be able to win the 5 vs 4 or 5 vs 3 against the players you didn't destroy who outskill the individuals in your premade.

If somebody queues up in a premade they should be ready to get mobbed by coordinated groups, and they should have teammates who are there to help them when that happens. Solo queuers don't have that. They just get destroyed, while likely listening to their solo queue teammates bitch and moan and do nothing to actually help them.

If you do manage to get these games to a 50% chance of either team winning, it's going to rely on whether or not the solo queuers who don't get absolutely destroyed can hard carry their teammates. I'm sorry but that is not my idea of a fun game and I think you'll find most solo queuers will agree with me. That is not a fun game for anybody. Not for the person who is no longer able to play because the 5-man removed him from the game, and not for the other solo queuers who have to carry the game while short a person or more. It's simply torture.