Most analyses I've read conclude that it's a bigger disadvantage for AL teams to lose the DH than for NL teams to gain it. That said, I've expressed the proposal before that the visiting team in an interleague series should be allowed one totally unrestricted roster move for that series. That would include anything, for example signing a free agent to a 3-day contract, putting a minor leaguer not on the 40-man on the team, anything. There would be no options used, no service time lost, no restrictions of any kind. That would help to negate any disadvantage to a visiting team from either league.