I used theese set ups: https://www.playstationtrophies.org/forum/f1-2011-vita-/234373-amateurs-guide-timed-perfection-trophy.html
Reading the forums I was scared about TT too, but they are not that hard. I'd say a 3/10 diff. The hardest one seems to be Suzuka, took me about 6 laps to put the best 3 sectors together and beat the record by +1sec. I kept the driving assists on, except brake prediction and steering. In Suzuka, this allow you to drive from 2nd corner to the end of first sector full gas, i mean FULL. The assistance forces you to reduce just the necessary to pass thru those corners.
If you know the tracks, beat the gold times woudn't be a problem.