I just got my Model 3 yesterday
I have a One Up rack that I've been using with an Audi Q5. I'll get a hitch mounted on my Model 3 in the Spring. I love the One Up rack. I had a Thule T2 previously. It's fine, but I prefer the One Up.
Regarding hitches, I've looked at the sites (and videos and forum threads) for both the EcoHitch and Stealth. The pros for the Stealth as far as I can tell are: it's lighter; the receiver attaches more easily; the receiver has a lock. The pros for the EcoHitch are: it doesn't stick out as far; the opening in the bumper is smaller and they sell (an overly priced) cover. A big pro in favor of the EcoHitch for me is that the company, TorkLift, is local to my area (Seattle) and I can go there to have them install it. The receiver on the EcoHitch secures with a bolt that looks like it's a bit tricky to insert due to the limited space. The local factor, along with the cover, are why I'll likely go with the EcoHitch.
For the One Up, I have been using it for the past two years for road bikes, trail mountain bikes, and heavy downhill mountain bikes (Whistler mtb park). I typically carry 1 bike, whether road or mtb, but have carried up to 4. Here's some of my experience that may be helpful to others looking at the One Up. They sell both a single and a double (each in normal and heavy duty), and then single bike attachments. You can put up to 2 attachments on the rack. What I found is that the single works great with any type of bike even a heavy DH bike. If you want to carry three mountain bikes, then I recommend the 2 place rack + 1 add-on rather than the 1 place + 2 add ons. I found that with 3 mtb's on a 1 place + 2 add-ons swayed (roll and pitch) while driving on bumpy forest roads. I called One Up and they said it was safe, but it made me nervous. 3 road bikes, not a problem with 1 place + 2 add-on, road bikes are not that heavy, but with 3 mtb's, the 2 place + 1 add-on is more comfortable. And for 4 bikes, you need the 2 place + 2 add ons. I started with the 1 place with a couple add-ons, but also got the 2 place. I use the 1 place the most, probably 90% of the time, but I use the 2 place when I carry 3 or more bikes now. If I had only the 1 place, I'd feel comfortable with 3 lighter bikes but not 3 mtb's.
Almost all my mtb friends are using the One Up now. If you look at the parking lots at the trail heads here, you'll see they are very popular.
When I have the 1 place mounted and folded up on my Audi, the parking sensors beep like crazy (I turn them off). It sounds like same behavior on the Tesla -- it causes the sensors to beep but otherwise no functional problem.
