I share your desire for the best performance but I believe it can, in time, be done without using SLI, assuming that were still a thing.
If it were to be implemented then Asobo and other sim developers may see that as the new way forward and stop attempting to optimise single card performance.
As things currently stand, they’re working on getting great performance out of one card with tweaks and substantive improvements such as DX12. This is way cheaper than needing two 3090’s. Careful what you wish for.