The OP should probably be aware that award space to the US in premium cabins is scarce, and relying on it as a strategy to get into F may well not be successful.

Whilst equally not guaranteed, the AUP (Airport Upgrade Price) route of asking for an upgrade cost at the airport check-in desk may yield a better result. If the trip needs to be taken anyway, it’s a no-risk option. If the sole purpose is to fly in F, then it’s not something I’d personally chance though.