I agree with you that Bonds was already a Hall candidate before the juice. He was at 400-400 and his W.A.R. was already over 150% of the average Hall-of-Fame left fielder. Had he played 5 more natural seasons, he'd have easily ended up at 500-500, and we'd be discussing his name with Mays, Aaron, Mantle.
The same is true for Clemens. Like Bonds, he started the juice at 34, and largely doubled his credentials in the 2nd half of his career because of it. He'd already achieved enough statistically to be inducted before that, and with 5 more 10-10/170K seasons, he'd have finished around 250 wins, close to 4,000 K's and been an easy first-ballot guy.
I just don't know about asking voters to judge their careers based on when we believe they started cheating and make extrapolations from there, while dismissing the guys who were only statistical candidates because of the juice (McGwire, Palmeiro, Sosa). To me, either we simply judge them against their era (which was known to have the P.E.D. cloud over it), or we exclude the known cheaters.