I am sorry to read of your frustration, but do you not pass through the Bronze stage before getting Silver? I know it's technically possible to go from Blue to Silver but mostly people have at least a period of time at Bronze, which gives a 7 day free seat selection period.

If that doesn't apply, I think I'd go with pragmatism here: pay the seat selection fee and smile that this would be the last time you would need to do so. Moreover Theoretical Seating may make the seat selection process even better when Silver (see relevant thread in the BA Forum Dashboard). Also on some flights by checking in the relevant thread on this forum, also in the Dashboard, you can make a judgement call as to how many seats will be swiped before OLCI. Note that only about a third of passenger OLCI in the first hour, depending on route, some routes it is a lot less. So depending on the specifics this may not be a big issue.