I wouldn't put a 1800 long tray on one for that very reason myself, I'll look at doing a shortened custom canopy on mine if I end up purchasing one.
I have a temporary 1580mm tray on mine at the moment,and it definately looks better length wise than the Shitty 1800mm toyota trays.
IMO a a lot of the trays on the market start to far back from behind the back window.
I have seen a couple of custom tray setups that are more forward , probably gaining 80mm.
I had a look at one with a 2m tray on it the other day, it was a bent chassis waiting to happen.
I asked the bloke that owned it how he went hooking a trailer up behind it. He then produced the longest tow ball hitch that I have ever seen and plugged that into the back.
It was just wrong, anything more than a half loaded 6x4 trailer would be asking for trouble.