I think the lighting issue is important but it is a subset of other issues.
Places of work in general need to comply with the Health and Safety legislation.
Areas where people are involved in games in semi-darkness may attract special insurance (think of a fin fair or circus)
The problem with the temporary lighting is that it can be "got at" by people simply tripping over it in the dark where it comes to ground after being run through tree branches overhead, for example.
Also several ground conditions can cause problems unless the part of the installation that traverses the ground is armoured/specced up for the part it plays.
I'm think of concert lighting rigs, but they are at less risk - the crowd generally doesn't come into contact with them, whereas with your lights they might.
So there is an issue of
1. segregation of the lighting rig/transformer/generator etc from the public
- vs-
2. the length of time it takes to erect
-vs-
3. the hazard the installer may face from high level work in trees.
As an employer you have a duty of care
As someone designing the rig, you have a duty of care
As someone managing a place of public resort you have a duty of care.
Add public liability insurance and any specialist insurance into the mix.
Add training of marshalls and reduction of hazard in poor lighting conditions.
Cover yourself with an adequately specified, sited, cordoned and marshalled rig.
Write a good Health and Safety Plan.
ONQ.
All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matter at hand.
I am not an expert on public lighting installations, or external places of public resort.
