Agree the slanted base is a death knell for any print. Also - the brim should really be sticking better than you are experiencing. You might go back and really wash the steel sheet with a few drops of decent detergent and really hot water; handling everything only by the edges, and using only fresh paper towels to wash and dry -- no hand towels, dish sponges, etc. And when installing the sheet, again, handle it by the edges because even one fingerprint will dislodge a print the size you are making.
@Vintage: where is that "Surface to Bed" option found in the UI? As far as I know Slic3r PE doesn't have the feature. A user must 'painfully' rotate the part fractions of a degree and reslice to check alignment. Or use the CUT method to trim an angled base.