Real time rear view!!

[Dunc6001]

Evening all, here's my problem?
Van with no rear windows.
Tow motorcycles on a trailer
'Passenger' would like to view Bikes (in real time on trailer) via iPhone/Android to check they are still i) connected to the van!! and ii) in an upright angle and safely in transit!!
Any advice/recommendations?
Thanks
Dunc

[marshalla]

Does it have to be on a handheld device ? A reversing camera & monitor would achieve the same effect and probably be easier to rig up with some temporary wiring and a false reversing signal to activate it,