Yes, I am a "crazy scientist."
Just trying to have an open mind and not be constrained by traditional, narrow thinking.
I should clarify. When I wrote "patch", I included vulcanized plugs like DynaPlug or something from Slime. I do not patch the tire from the inside while out riding. As mentioned, the combination of tubeless/sealant has always worked for me, assuming I have sealant in the tire.
And, yes, depending on the size of the cut, tubeless tire can be patched. For example, I had a sizable cut (~4mm) in my new Panaracer Race A Evo 3 (name is too long) tubeless tire, but the sealant worked well enough to help me ride home, which was ~10 miles. I called Panaracer and was told that patching the cut might not be a good idea in the long run because of high pressure -- Panaracer's customer service was so good that it sent me a replacement tire, free of charge.
As far as high pressure and tubeless go, it's worked for me. Of course, I ride mostly 28mm tires; even the 25mm Schwalbe Pro One I rode tend to inflate up to ~27mm. Thus, I don't use as much pressure in the tires. Usually, I ride in the range of mid/high 80 PSI (~6 bar) in the rear and low/mid 80 PSI (~5.5+ bar) in the front.
In regard to sealant refill, the incremental addition isn't quite cumulative in that sealant does evaporate. So, when you refill, it's not as though you already had 40g in the tire and you are adding another 40g, with 80g total. That said, there will be some remnant of previously filled sealant in the form of dried rubber. Also, keep this in mind, once you already have sealant in the tire, after some time, the inside of the tire gets coated, which means your tire should be well sealed. My subsequent refill I tend to use a little less sealant.
My 2 cents. FWIW...I'm ~6'1" and 210 lbs.
I've been tubeless, road/mtb/cx/gravel, for the last three years. For road, I've had a total of 4 flats, and was able to continue riding 3 times. 2 of the 3 times I "heard" the flat, and the last one I didn't know until I got back to the car. The one time I couldn't get home was because of low/no sealant as I had forgotten to refill -- had been 3 or 4 months, I think. I never take spare tubes on the ride, but do carry CO2 and patches.
In short, I'm pretty sure you can get away with not carrying spare tubes, but it's still a good idea. All 4 of my flats were cuts from running over debris/glass/nail. Never had a pinch-flat. Never burped on the road -- a combination of high pressure and proper tubeless rims with some type of anti-burp bump. My rides are usually between 30-50 miles.
Oh...I still don't carry spares. Just have a few tools in the back pockets.
You brave brave man.
In our group I'm the crazy scientist/mechanic and I wouldn't leave home without at least one conti supersonic inner tube.
You said you leave home with patches and a pump. Can you patch a tubeless tire? Do you do it from the inside or the outside like I've seen some tubulars repaired?
I heard many people advise against running tubeless on road bikes because of the higher pressures. Like sealant doesn't work well at these pressures. What about all that sealant weight? Like after 4 refills doesnt the tire weigh like 100gr more?