Closest point outside agent radius padding

Is it possible to get the point closest to an obstacle outside the agent radius padding? Use case is a point and click type of game where navigable spaces between obstacles are quite narrow due to padding added by the agent radius. The player might click on a point that looks to be between obstacles, but if that point is closer than the agent radius to an obstacle, navigation will be rejected, even if it is outside the actual obstacle. This behavior is kind of expected from a technical point of view. However, it would be nice in that case to have the agent navigate as close as possible to the clicked point, not leaving the player frustrated because he/she thought they clicked on a valid space between obstacles.