Cheaper option to the BIG panny is the Sanyo XF71 range with dual lamps (10k lumens) or XF47 (15k lumens) below that your on 6.5 to 7k lumens for single lamp units, the 7k lumens PLC-XP200 is £5k ish with a lens. XF71 is £10k ish + lens i think and the 47 is £13k + lens This is what i would be looking at probably with a Pro Audio sound rig something like
Funktion One (UK) set up with an audio processor. What sort of budget has your firend got for this system?
Re HDMI length anything over 20m is going to need somthing other than standard you can go 100m over fibre at acost of £1000+ or 80-90m over Cat6 with good baluns (£300 a pair) If its for a one time gig best to rent/hire gear have it set up and then taken down after (a bit like the real glastonbury) but you will need a pro spec sound system to replicate the audio, just like the one linked too. Drop us a line if you want a quote for setting this up for you, sounds like fun!