The biggest problem you might have in towing "just over 1000lbs" is that you will find yourself frequently checking your rear view mirros to make sure you haven't lost the trailer. Your ES350 engine is rated at 272 h and it's curb weight is 3580 pounds. When towing my loaded 4'x8' utility trailer behind my 240 hp, 3759 pound 1990 LS400, I could not tell by the way the car accellerated or handled that miy trailer was attached to the car.
You might notice that virtually all the people who tell you not to tow have zero experience towing. I've towed stuff all my life including 40+ years ago when I was a "kid", had a commercial license and towed really big stuff behind a commercial rig.
Fear not. Just follow the your owners manual and be careful. You will want to power your trailer running and brake lights from your car battery or underhood fuse box and only "trigger" your trailer brake lights and turn signals from your car's brake and turn signal light harness. Buy the appropriate trailer light wiring harness to accomplish this.
OK, I had a Kurt hitch installed with the wiring kit installed according to instructions. Hooked up my trailer with the jet-ski and drove around for a while in different conditions and speeds. Around town I kept the transmission in 4th so it wouldn't be going in and out of OD. Out on the Hwy at 65 there was no noticeable feeling that the trailer was attached. Launched my Jet ski today without any problems, very easy.
Now the test, loading the ski on the trailer and pulling it out of the water up a rather steep ramp. No problem what so ever........like it wasn't even attached.
Thanks all for the advice, email me if you have any questions. PS also the car stay's completely level with the trailer and ski attached