For one, a great big bottle of ibuprofen. We don't have fw rays, but coastal SC is full of sw rays, and believe me, the little ones are the most dangerouse, the stingers are much sharper and thinner than big rays, and they know how to use them.
As far as filtration, you could use pretty much any type of filter you want so long as it does these three things at least:
1) Mechanical filtration, removes gunk and debris from the water before it degrades into pollution. Keeps water clearer.
2) Chemical filtration, namely, activated carbon, like Black Diamond or Matrix carbon. I also use Purigen b/c it's rechargeable.
3) Biological, removes ammonia and nitrite via bacterial growth.
Rays probably like a decent amount of water flow, so don't be afraid to put a lot of filtration on the tank. A turnover of 10X the tank gallonage per hour is a good rough figure, via one filter or multiple filters.