Quite likely there may be a warranty issue if you don’t use copper. I would use copper without a doubt. I am a co-owner of an electrical wholesale distributor, been in the business my whole life. When it comes to hot tubs we always advise copper. And all of my customers..electrical contractors...
Here's what I use..and sell...
Atlas Lighting ILW76LED8 - 8' LED Enclosed Fixture (Available in 4' as well). Google this up, go to their website...Fine commercial top quality fixture. Sells for around $280...not cheap but having the proper light and fixture above our special cars is of utmost...
As I mentioned above I replaced mine with a Davies Craig....part # EBP25...alt part number DC-EBP9005...bought from Hoerr Racing Products in Illinois. ....309-691-8789....took about a week.
Paid off our house a few years ago. Greatest feeling...knowing you have a roof over your head no matter what may happen. And with no other debt, it’s becomes a very calm and peaceful time. It just relaxes you. It’s interesting when you get together with friends and family and the conversation...