Baljinder ji, dogs are very sociable animals and it'll be very unfair to keep them alone all day. The good thing is you are at least meeting the exercise requirement of this dog. I don't think bringing another dog will solve this problem. It will rather increase the amount of care you need to direct towards them.
Rottweilers are very trainable dogs and extremely intelligent. My advice will be to let your dog be in the restaurant premises.Your dog will see people coming in and going out. He will see different people and hence he will become a very sociable dog in the future. I think, you should take him in gradually. For one hour for one day, 2 hours another day and half day for another. When your dog stays with you in the restaurant, the bond between you and your dog will become stronger.
Most people now accept dogs and very few would have apprehensions on the dog being in the hotel ( saying on the customers perspectives .