I did simple one-handed squeezes (basically a Uli without pulling forward much) for a while as my first girth-targeted exercise. I mixed them into my jelqing session. Jelq a little, do a squeeze, jelq some more, etc.
You might be building more pressure than you need now. Also, try to adjust the skin so it isn’t stretched quite as tight when doing the Ulis. By this, I mean pull the skin up the shaft before taking your grip. Create some slack where the shaft will expand when you Uli.
High pressure under tightly stretched skin = red/purple spots.
Oddly, the more consistently you PE the fewer spots are caused by equally intense exercise. For example, I get absolutely horrible spotting and bruising on the first day of doing Extreme Ulis. The second day is similar, though not quite as bad. By the third or fourth day, I get no spotting, even doing more sets. This “immunity” to bruising continues as long as I do the EU’s every day. Take one day off, then resume, and I get bruising again. Several days off seem to supersensitize things worse than only a single day off. This phenomenon baffles me.
If you are concerned about avoiding long-lasting discoloration try to avoid techniques or schedules that cause spotting every workout. My discoloration worsened considerably when I kept going for many weeks despite bad spotting each session. The discoloration will fade (at least some) once the exercises that caused it are stopped, but it takes a long time - many months.