nice but i think you should make one big container

Rather longer loads, like in the video showing the real thing; it's the length of the loads that gives the side loader advantage over regular fork lifts.

This is correct.

And i have another reason for no heavy loads. When there is to much load on the forks, the sled is pulling out the driveaxle of the winch a 16l axle with endstop would be cool.

Hadn't paid much attention to the progress of this creation. It's a very cool machine. Well done

I am not so sure if I like the sliding mechanism, but it seems to work well enough. On the other hand, I have no good idea how to fit something else in this small space. I guess the tilt of the lift results from general play in the slider??

Yes, this is the problem. To solve this the sled should be longer, but there is no space. Maybe with some adhesive tape to reduce the gap between the sled and the chassis would be an option, but unfortunately lego doesnt sell adhesive tape

This just wouldn't get off my mind. What about something like this instead of a pure slide:

with this the sled has the same play like my actual mod, but thanks for this idea. this solution i had not in my mind

Hm, you are probably right about the play.

problem is solved by two simple 1/2 pins

Decreased play. Best solution ;)