Thoug I would not rule Dragon beeing a crew member of Roger, I think it is highly improbable. In Roguetown, Smoker said he had not seen him since Roger's execution. Whatever he did at that time, had he been a crew memeber, he would probably have been more recognized (though smoker was still a kid at that time).
Then during a meeting of the gouvernements part of WG (as vivi is about 10 and wapol already king of Drum), Dragon is first referred to as a rising threat to the current world order. Had he been a Roger's crew member, he would probably have taken more seriously way sooner than that. (though having someone as Dragon as navigator for instance, assuming he can control weather with some kind of special power would definitely kick ass)
Crocus (assuming is not lying) could not possibly be Roger's doctor as he said having been the twin's cape guardian for the last 50 years.
Tom is only said to have built the ship and I cannot remember any mention of date between the day he built the Jakson Oro and the day the WG first arrest him. I would not however use the "had he been a crew member he would have been charged for it" argument as it was clearly said that the WG only charged Tom in order to get the plans of Pluto, not for the sake of arresting him. Still, the single fact that he was still on the island teaching Franky and Iceburg would rule out the possibility of him beeing Roger's on-board shipright.
I like the idea of Mihawk having been Roger's swordsman. He possibly was quite young but you have to remember Luffy and co are currently in their high tenns, early twenty, given Mihawk's serious abilities, he could have been there at some point. It would also explain why he became a shichibukai though he does not seem to care much about the WG.
Kureah is for me one obvious choice as Roger's doctor and I like Zeff having been is cook. Though Kureha seems to know the old pirate, Zeff doesn't mention anything about roger. Still I like the idea of Luffy's crew beeing somewhat similar to Roger's.