Rather than wading through a full RFP process, consider an abbreviated method. Explain to an experienced service provider the outlines of what you are seeking. Provide them with as much detail as you can and ask them to share with you what they think they might be able to do for you.
The advantage of this approach is that you can much more quickly make progress and you can shape an arrangement that is the most beneficial to both sides.
The disadvantage is that you lose a sense of what the competitive market offers. This disadvantage may not be as bad as it seems because quite often responses to proposal requests come across as quite similar. In the end, savvy practitioners can ask better questions and give better answers face-to-face in a dialogue then you can learn from the rigidity and slowness that may characterize some RFP processes.