There don't seem to be any extension cables available longer than 50 metres. There are obvious problems with trailing cables. If on the ground they would need a good level of mechanical protection if in a walkway. RCDs would be a must. Get a qualified electrician.

Generators bring some problems; the mains output is usually 'dirty' with small industrial generators and not all PA equipment can cope, so you may have to supply extra filtering. Our last experience caused the level indicators on the mixer to indicate max all the time. Noise from the generator can be a problem.

Lighting uses a lot of power - is the event in the daylight?

Just some thoughts

Stu