Great advice from the above.
My 'apprenticeship' on a lugger, first yacht, a 'clansman' - long keel, now a peterson - longish keel. So I fully concur with above. In reverse, an engine is just a brake - rudder is useless.
Use prop walk, of which you must have in abundance with the offset. Do you have a 3blade or a 2 blade? = 3 blade is better but a bit more drag and not worth the expence to change.
Practice and practice and then, realise that every time you enter into the slip, it is different to the last.
Welcome to the club- I put fenders
out both sides and enter the slip --> very slow.