Yes, I would say that 316L is the preferred grade (see this post), but I found it difficult to source suitable 316L bolts in the UK as they tend to be sold as ‘A4’ which is defined by Westfield Fasteners as:
“A4 Stainless Steel - Also known as grade 316 or 18/8/3. A higher corrosion resistant, marine grade of stainless steel.”
I believe A4 may be 316 or 316L (low carbon). My plan, if A4 was insufficient, was to move to Duplex which is most likely overkill, but it is at least a grade that bolts are sold in. Given that Gerrit has been using 304 (aka A2) without issues, the assumption is that A4 should be more than sufficient.