cover letter writer required for job proposals

I need a cover letter writer to help me in writing job proposals. I work on upworks as a developer and as you also know a tedious part of freelancing in such platforms is writing proposals. I need someone to write about 5-10 proposal a week for me, I'll pay around 100-200 per proposal and if I get the jobs out of any proposals I'll pay double for those.
Here is some other info:
1. The proposals should be custom written based on each job and not a fixed script please write ( proposal in caps) in the begining so I know you have read the description
2. We need to create some basic structure to use in these proposals.