[Semiapies]

1) Again, the preposition isn't a problem.

2) Then use "whom" if you like. I really can't be bothered to care, as the purpose of language is communication, not structural pedantry. Remember your Elements of Style - "Break any of these rules sooner than say anything outright barbarous" - and note how even presumably well-educated people here find "whom" awkward and stilted in that usage.

[endtime]

I'm not taking a position either way - just stating that your suggestion doesn't actually change anything in question.