Fat Bike Question: Will 4 inch tires work in soft sand, or do I need wider?

Planning to do some riding in very soft sand on the Gulf Coast of Florida. I've been trying hard to find a bike with the widest tires possible (e.g. 4.8 inch). However I'm coming up empty despite lots of searching on eBay, Bikes Direct, LBS retailers, Craigslist, etc etc.

However there are bikes available that can take up to 4 inch tires. Anyone have experience riding four inchers in soft sand, and might be willing to share? I'm driving a long way to the coast, and won't have the opportunity to test in advance.

Would be grateful for advice. Thank you!