I'm not too concerned about the right-back issue. If he doesn't know already, then by the time the season starts Gary will know who he can play there. If he sees there's a problem, it should be relatively easy to sign one, possibly on loan. I haven't been to any of the games, but it seems like Gary favours 4-4-2, which requires full-backs to be more defensive and relies on wingers or wide midfielders to feed the front men. So I don't think we need a pacey, attacking full-back, which are a little harder to find.
Certainly, we have found in recent years that it's more difficult to find decent strikers than defenders. Even in the past five years we've had quite a few good defenders, but only Ryan Lowe and Jake Cassidy (in his first two short spells) have impressed up front. I'm hopeful that the four we now have (including Cole Stockton) will deliver the goals this season.