We are 57 and 58. I'm 5' 8" and my lovely wife a bit shorter. Our Triton is a 430 in which we sleep across.
The critical height seems to be 5' 10" for sleeping across in a 2.0m van so you should be fine.
Having said that we previously had a wide bodied Troll and sleeping across in the longer bed was very nice. Mrs eribaMotters who sleeps across the back found the extra space most welcome.
We like sleeping across as it means you can sit up in bed without having your head against the rear window. It also means you can have a front seating area if in a Triton and if in a Troll then it is bigger.
Colin