Force grasps to be planned from above a surface

[jsll]

As can be seen in the image below, the simulated annealing planner always wants to plan from below the object, although I have an obstacle there which should prompt it to plan from above. I have tried tweaking the simulated annealing parameters to prompt the sampler to sample grasps from above but with no luck. Are there any tips how I can force the planner to stay above the table?