Octave

Hi - thank you indeed for the great review. Forgive me if it is implied, but can the Solis provide PV power (blended with mains and battery)to the non-essentials when grid is on? Like the Sunsynk can....I'd like to be sure I can use as much of the solar capacity as possible and the feature to use excess PV power on non-essentials is a great way to maximize the investment in panels....

Disclaimer: I don't have much experience with aux (yet, by next week my father in law's geyser will be on aux)...
I would do as you're suggesting- all non-essentials on aux, wire and program correctly, but include a change-over switch to Eskom. That way, you manually manage your loads while on aux (and correct setup will disconnect aux below certain battery level), but you still have option to connect direct Eskom in case you need to run beyond pass-through limitations (seldom, but best to future proof from the start)...
Best of both worlds 😉

I'd like to share my experience with my aux port (Smart Load).
I think that the main reservation behind it is that there's a lack of experience with it in general.  Also to wire it up is a proper mission since you have to totally divorce whatever is wired to it from the rest of the house or it causes issues.
I've personally had my six geysers put onto Smart Load purely to force them to use the sun and leave my battery alone at night.  I think if I wasn't on a parallel system it would work perfectly fine (We still have some kinks to work out and are converting some to gas).  I have also sometimes turned on the "On when on grid" function to force it on when I have a lot of guests.  For me it's meant the difference between 2kW draw and 20kW draw and my one battery lasts a lot longer at night.  I can now even pick and choose which one runs:

So for your case I definitely recommend it, but find yourself a brave... no brave is the wrong word... a determined electrician who is willing to do the leg work and wire things correctly.  If you so much as share a single neutral it's a bugger up (which we had in my case).  The electrician I had actually popped one of my aircons.

I can do this in 2 weeks time extremly busy at the moment i would not go smaller than 3kva if fridge compressors are involved. Below picture is what you need. 3kVa 24v 2.75kWh LFP.

Pm me if you are interested.
 

Be careful if a 1000W inverter does not have a 2x short term peak value. It might not start a fridge. 

In terms of useage per day, well you got that for the summer. Typically 7 to 8, peaking at 11. Use that same method, whatever it was, for June/July.

Sizing for the winter will probably mean that you have excess capacity in the summer, but that's better than not having enough in the winter, especially the way that the load shedding is going. 
There are really two numbers that you need. One is the consumption in a day. You have a handle on that. The other is the peak consumption at any point in time. 
Consider my system: rated at 4.6 kW. So "background noise" is about 200W. Then early in the morning the heat pump turns on, and now we're consuming 1.7 to 1.8 kw. Somebody feels like a cup of coffee and the kettle goes on whilst the heat pump is running. Now it's 3.3kW. So too many things on at the same time, especially big loads, and you can hit that limit and either the inverter or the battery, which ever has the lower limit, will shut down to protect itself.

You are already doing a good job of managing your electricity usage. The advice is often given here that one should tame that beast first THEN get the solar installed. Taming the beast, which you have done, saves you money on the PV system.

Once your system is up and running, there should be some kind of monitoring tool. EG for my system

This is what you use to optimise the use of the system. Close monitoring early on will let you see how much different appliances draw, and will help you to "move" loads around using timer switches. Note the sudden jump at about 8:00. The heat pump was already running, then the kettle gets turned on and total load goes up for a few minutes. Don't come to me for supper! I can bore people all night long showing them a graph and pointing out where the pool pump turned on and etc.

You've done a good job of keeping consumption down. Size the system for winter peaks.