If you believe your dream client is always right and that it’s your job to sell him what he wants without question, he will never perceive you as a peer. You will be seen as a commodity, just another salesperson operating on a purely transactional basis.
What you want is to be perceived as a peer. A peer challenges his dream client’s thinking when it needs to be challenged. A peer makes sure that whatever he and his client work on together becomes the biggest value-creating initiative they can dream up. A peer does not avoid the difficult issues surrounding the results a client wants.
If you are afraid you will lose your opportunity by bringing other stakeholders into the decision-making process, then you’re not really in control of that process. You’re not giving your dream client good advice and, I am afraid to say, you are not a peer. A peer doesn’t run from additional stakeholders but strives to build consensus among them.