I have two small T graeca Moroccoensis youngsters, I have built a table 600 X 500 and put a mix of calci sand and desert sand to a depth of 2" Also slate for food to go on, a shallow saucer for water and a half barrel for shelter, at one end I have a 60w basking light, How high should this be above the torts and what temp should i be looking for at that end of the table?