First, relax the rules. Think about the four or five behavior requirements that are most important to you and his mom, and enforce those consistently. If he is playing in the sandbox and hits another child, for example, then he comes out. Removal is the best way to help a child of two learn the rules of social interaction. Second, try to withstand the tantrums.
Children have different temperaments.
Some children scream and cry over seemingly little things. That's who they are. This seems to be the case with your little charge. It is particularly difficult to deal with a highly sensitive child who gets upset often, but it has to be done. If you have explained the rule and have put the disciplinary tactic into place, then you have to step back and let this child have his reaction.