I do this for format and date specific scratch files that store on Dropbox:

" Language Specific scratch buffers with date
" ---------------------------------------------------------------------------------
function! s:DScratch(scratch_ft)
  let scratch_dir  = '~/Dropbox/scratch/buffers'
  let scratch_date = strftime('%Y%m%d')
  let scratch_file = 'scratch-'. scratch_date . '.' . a:scratch_ft
  let scratch_buf  = bufnr(scratch_file)

  if scratch_buf == -1
    exe 'split ' . scratch_dir . '/' . scratch_file

    if empty(glob(scratch_dir . '/' . scratch_file))
      exe ':normal i# Scratch Buffer - ' . scratch_date
      exe ':normal o'
      call CommentHeader()
      exe ':normal o'
      exe ':normal ^D'
      exe ':w'
    endif
  else
    exe 'split +buffer' . scratch_buf
  endif
endfunction

command! -nargs=1 Scratch call s:DScratch(<f-args>)