The lines won't show wind up, but they will highlight if something breaks. In the drivetrain, you'll find about 5 degrees of lash between the front and the back wheels before they move in unison; wind-up will put tension between them but won't noticeably vary their relative positions and will be relieved by one of the wheels skipping in relation to the other.
If that wasn't the case, even with the allowed ~2" of variation between the tyres, you'd be breaking stuff in no time flat, under normal usage. For the most part, wind up in Ferrets/Saracens/etc. is overrated and is rarely a problem, unless the tyres are way out of spec, or if you're doing lots of tight turns on a hard surface (such as donuts). In general, the running gear on these vehicles are pretty robust and are most likely to fail from a lack of adequate lubrication, rather than mechanical influences. That being said, they are old and things do just break on occasion.
I'm hoping that yours is a Mk 1; 4 people in a Mk 2 would be way too cozy for my liking They do get lots of attention though, for sure. I can never go to the supermarket in mine without gathering a crowd around it.
Cheers,
Terry