I'd have bought an MS18 but just don't trust Imalents warranty and business practice. Ive only bought one light from them (UT-90) and it was stressful. If I had more confidence in them I'd definately own at least 3 or 4 Imalents. Just saying it as it is.
I am sure I'm missing something but why not get an Olantern by Olights, you can charge it from any USB source, powerbank etc. Or an LT1 with 4x18650 cells that can be recharged from solar. Great job I guess I'm just missing the point.
One Olight torch I bought (MiT-Raider) came with non-rechargeable CR123's. I replaced them with Olights rechargeable li-ion cells CR123A part no:ORB-163PO6 (650mah). Just a possible option, they have been great cells.
You kinda want 15ish to 60 thousand Lumens I would think. DX-80, X80-GT, MF01s, Maruader2. The question might be how 'long' do you want to light up this football field?