Caramels without cream or condensed milk?
You should be able to use butter easily, there are good caramels based on butter. 

As a starting point in reengineering the recipe, I would try 1/3 of the cream amount as butter (by weight). So 3/4 * 240 g (1 cup of cream, rounded) / 3 = 60 g butter. Cream has about 33% milk fat, and the water in it evaporates anyway when making the caramels. You'll obviously have to test it and tweak it until you have arrived at the best substitution ratio. Removing the oil may simplify things, it's unlikely to have much contribution when you are working with butter.