Since Courseplay 5 has been released on ModHub, it is probably a good idea to record a harvest one time, so that you can automatize the sugarcane harvest. You can also try to forego the sugracane trailer and just drive alongside the harvester with your roadtrain, however filling up the semitrailer at the back is bit more difficult because your truck will have to drive slightly in front of the harvester, making it easy to block the harvester if you don't pay attention. Pay attention that your trailers are in the designated purchasing zone, otherwise you'll drop the sugarcane on the ground. To unload those at any purchasing point you will have to tilt them, you can't just unload them like other trailers. With the roadtrain configuration you can collect 133,000 l of sugarcane. When your trailer is full, drive it alonside the sugracane semitrailer and drop the sugarcane in those trailers (by adjusting to full height then using left mouse button sideways to tilt the trailer). To help you here, adjust the height of the sugarcane trailer so that you can see the outline of the trailer, adjust cruise control on the tractor to 10 kph and keep alonside the harvester. The issue with that is that on turning into unharvested sugarcane rows you can't see your tractor anymore, because the sugarcane grows way higher. I found that the more efficient way is to have both sugarcane semitrailers in a roadtrain configuration and use the height adjustable sugarcane trailer (MF3012 - 28,000l) alongside the harvester (hired help). The trailer should not be too high and have that 'triangle hitch' if you want to attach it to the back of the harvester. The issue with the sugarcane trailers is that due to their height the pipe collides with the front side, so you can't reach the hitch.

Agroliner HKD 402 - 31,500 l (this is a Mod by CatFan18 Mods - can be found in the ModHub as HKD 402 Pack)

Fs19 sugarcane harvester trailer mod