The greatest obstacle to any Imperial Federation including India is that India would effectively overpower the rest of the British Empire in population and, once industrialized, in industry as well. The thought of brown people getting that much power goes against the racism of the time, and the other proposal, to make representation based not on population, but on something rather more vague, would anger the Indians, who would want fair representation. This really makes any sort of Imperial Federation with India in it difficult.
My challenge to you is an Imperial Federation that includes India, and goes Indian in the process.