there's probably as many different sand situations as there are snow. I did the same w/ a mountain bike & 2.25 tires. opened up lost of opportunities. but there are limits. I just work with what I have & go where I can. getting a MTB was easy to add to the stable. a fat bike is a whole other animal. thanks for sharing, looks like a fun area!
as for tire pressure, the lower the better. for me, if I remember correctly, 25psi rear 21psi front works for the softest stuff I try
for
forest roads & narrow dirt trails, 30 rear & 25 front is good

now that you have this bike you may be tempted to go places you've never tried. probably not hilly & mountainous w/ roots & rocks & no ice like up here. I didn't start falling & crashing until got a MTB. be careful if you get tempted to ride the edges where the sand is mixed with other stuff. yes you can ride on it but you might fling a stick into your spokes or derailer & down you go
approaching beach, I'm good to a point & then I have to walk it

and good luck cleaning the sand from your drivetrain ;-)