Croozer bike trailer optimalisation for less tire detoriation We love to travel by bike. Last summer we did a trip of about 650km on mostly asphalted roads (with quite some medium long climbs and descends) with our son in a bike trailer (type Croozer, see picture below).

During this trip we had to change the outer tires of the cart two times. The first change could be related to previous use (intensively used for commuting), but after another 400km we had to change them again due to wear (all rubber deteriorated on the outer tires).
As you can see on the picture above the cart has wheels that are a bit tilted, making it more stable. We noticed that the wear appeared not in the middle of the tires but more towards the inside (due to this tilting).
The cart is coupled to our bikes with a kind of spring mechanism, which allows free rotation in all directions and some vertical and horizontal movement. The spring has some negative effects. You notice the effect of that when braking (the cart itself has no brakes). Going downhill the cart tries to break out. Would changing this to a ball hitch contribute in solving my problem?
The wheels each have their own axle that makes it easier to remove the wheels. This is handy when taking it on a train or parking it somewhere (you can lock the cart to a post and remove one wheel so nobody can ride away with it). However, due to this system there is a little bit of play on the axles. The tires are size 20 x 1.75.

The wear on the outer tires makes it difficult to take longer trips because you need to take spare outer tires for every 400km you plan to do. I was wondering if I could make adjustments to this trailer in order to improve the lifetime of the outer tires.
The wear was a lot slower when using it for commuting (no steep descends on the road) compared to our holiday trip (climbs and descends of 5%, load at 80% of the max load allowed by the manufacturer).

What I found on sheldonbrown.com already helps a bit in determining the tire pressure. I think I will inflate them a little bit less. I always used maximum pressure (4 bar, 60 Psi) so I would need less force to pull the cart. However this can contribute to faster wear apparently:

Trikes and two-wheel trailers are very different from bikes, because they don't lean in corners. Most tire wear comes from cornering forces. On a bike, these forces act on different parts of the tread, according to how far one leans into various corners at various speeds.
With a trailer or trike, all of the wear is concentrated on the middle of the tread. If you overinflate the tires, you'll be riding on only the very center of the tread, and it will wear rapidly.
In addition, wheel alignment is never going to be perfect. As a result, the paired tires will always &quot;scrub&quot; a bit. If the tires are rock-hard, this will cause rapid wear. If the tires are softer, they can flex slightly sideways to accommodate the scrub, without wearing the tread off.

However I want to improve lifetime further. Which steps can I take next?
My VidaXL yellow/black soft bag trailer wore the tyres due to parachuting effect caused by the empty compartment and top cover letting wind inside. Also the axle retainers were wrong way round promoting too much toe out, I flipped them over and there is some toe-in, that decrease when pulled along. I now leave top cover off empty trailer so wind doesn't drag it down, top cover is placed on floor and used when it is full of cargo. It is also imperitive to angle the hitch downward so the trailer is level or front low which is better, a trailer that planes like a boat also put undue load on tyres. The towing bike is 20x4 fat bike