I had an Avante 2011 runner a few years ago and tried to find a good setup for it, before I knew what I was doing. I've since sold it, though
If you're running on astro/concrete mix, then you're looking at a high grip surface. On 2.2" rims, the Avante will have too tall a ride height for that surface, since the car in its original form had smaller rims. Since the Avante does not have much or anything in the way of adjustable shock towers, the only way for you to really drop the ride height would be to put downtravel limiters in the shocks. Or, you can go back to the stock wheel size (Hotshot wheels and tires may suffice here, if you add foam inserts), or both. A typical ride height for a turf car is in the 16mm range for a 4wd buggy. If you find that you have to add so many downtravel limiters to the shocks to achieve that (with 2.2" rims), that you end up with little to no suspension travel, then you should either use the smaller rims or adjust your driving to be smoother so that the car doesn't roll as much.
On the outer front caster block, move the camber link from the lower hole to the upper hole. This will increase the front roll center and help to reduce chassis roll at the front. You may also want to remove that front tower and mount the front shocks directly on the gearbox, as it was done in the original Avante. This will make the shocks lay down more, which has three effects: 1.) reduced CG; 2.) a little bit of push on corner entry (less tendency to roll over on corner entry); 3.) more mid-corner steering (more chassis roll mid-corner).
At the rear, there's not a whole lot you can do, other than to mount the shocks on the inner hole on the tower. This will numb the rear a little bit during cornering, making it less twitchy and therefore less likely to flip over. There are games you can play with the rear arms, which allow you to adjust both the wheelbase and toe-in via the tie rods at the front and rear of the arm (the front arms also allow this). However, I would urge caution here. There's not as much adjustability as it looks like, without making the dogbones pop out, so I'd recommend not adjusting the arms.
I see that you have the Hi-Cap dampers. The suspension geometry on the Avante is a little weird, so I don't have a good suggestion for oil and pistons. You could start with 40wt front/rear oil and 2 hole front/rear pistons, and then take it from there. Chances are, the oil and piston adjustments on this car is where you'll spend most of your time, since the rest of the car doesn't offer much in the way of geometry adjustments.