Ive always looked at him as the next Ryan Braun. Maybe not quite the threat on the bases, but a great all around hitter. So LF seems like the most logical move.
But, if Dustin Ackley can play second base, then so can Rendon.
Personally, I think Lombardozzi fits best at second. Mainly because of his ability to hit leadoff. Nobody else truly projects there, so it helps his cause tremendously.
Id try Rendon out at a couple spots after the season in extended spring training. See where he looks best at, aside from third, and go from there.