Which road rear hubs have 135mm O.L.D., disc brakes, are quick release and have at least 32 holes?

You can add a 5mm spacer to the NDS of any non-disc 130mm QR road hub and dish for 135mm. I've done this a few times with 11s 105 and ultegra hubs. But then you'll have to give up the rear disc brake. is there a center mount for dual pivot rim brakes in the rear? There are clamp-on (?) brake bosses to add posts for cantilever brakes but...

As far as carrying a heavy load, you might be better off with a mtb hub which is designed to be more robust. You can also bump up the spoke count. I've laced up 48h 5X wheels before. Velocity makes 48h rims in 700c.

12ga spokes are an option. If you go 36h, lace them 4X. Also consider distributing some of your load to the front fork or a frame bag if possible.

From https://easymountainbiking.com/can-you-fit-an-11-or-12-speed-cassette-on-10-speed-hub-on-a-mountain-bike/

"Standard Shimano freehubs are 33-34mm. Now, you may have some older mtb 11-speed cassette that needs a bigger freehub or you simply want to fit a road cassette on it. Believe it or not, gravel bikes are usually best with wider mtb hubs and road biking drivetrain so adaptations are sometimes a tricky thing.

You should check exactly how much you need for it to have 34.95mm of space. There are two ways I usually get those missing millimeters.

Depending on the manufacturer, you can either grind some material from the freehub on the bottom of the splines or grind some from the biggest cog on the cassette. I prefer modifying a freehub because it’s easier to keep the grinding surface level. If it’s not level the cassette won’t be stiff enough and might damage the freehub bearings and attachment bolt. Which can then result in wobbling and gear skipping.

You should be careful about how much space you have from a cassette to the wheel spokes. If the cassette comes too close you might damage them. Although I’ve never seen this problem on a mountain bike, only on road bike wheels."

The Velo Orange rear hub comes in 32 or 36 with the correct endcaps for 135 QR. You choose the freehub you want, 11speed road is an option.

https://velo-orange.com/collections/hubs/products/disc-rear-hub-silver-and-noir?variant=31841972715657

Halo make an equivalent part (WL) but only a 28 drilling.

A DT Swiss hub with the correct endcaps would work, as previously noted.

You could buy one of the Bitex Road Disc hubs that Pacenti sell and fit the 135QR axle kit, also available from Pacenti.

So you have lots of options, and I've only listed a few.