With using the bar weight only reduce you squat and bench press to 50% or 60% as when performing fast sets of 3 which powerlifters often in between their heavy sessions. You will probably find that bench feels much easier.
When I do fast sessions such as this I now use ~60% for the bench and ~40% bar weight for the squat which equates to ~65% when taking total body weight into account or ~60% if calculating the body weight at 80% as rj24 mentioned and which I think could be about right.
Similarly if altering the bar weight to 80% RM for each above exercise I get out a few more reps with the bench.