Sometimes you have to play with the cards your dealt, rather than the ones you'd like. It seems you would not be the only wing official to encounter this issue, so it should not be a surprise to game management. It might be a practical idea to accompany the Referee with his pre-game discussion with the home Head Coach, and address the issue, explaining you (both) understand the problem and are willing to HELP THEM accommodate the situation, but NEED EXTRA cooperation and assistance from the entire coaching staff to keep back and out of harm's way for the benefit, and safety of both coaches and players.
Having broached the issue, specifically, beforehand in a genuinely non-threatening manner, opens the door for ANY subsequent problems to become a matter for the Head Coach's involvement and responsibility. Hopefully the HC's response will be one of cooperation and he will alert his staff of their necessary reaction and response and the problem will be minimized, if not eliminated.
If he chooses not to respond positively, or if his assistance doesn't provide suitable adjustment, you have a witness of your "non-threatening", positive suggestion, and there shouldn't be any surprise with whatever (appropriate) action you take, if necessary. Somewhere along the line, however your organization addresses game management about field conditions, this issue should be brought to game management's attention.