There are a couple of families in the area where I live with that last name. Perhaps a relative?
I would not rule it out
Not a custom plate, but…
California is about to run out of its current series of license plates. The format is 1AAA111. Some lucky individual is going to get 9ZZZ999. That would be a fun plate. 
Two in a diner parking lot this morning:
IBDBEST
LUV BLTS
ACORNS
Might be a fan of the proverb “mighty oaks from little acorns grow,” or might just really like oak trees.
On a white Subaru Crosstrek: WHALE B8. Whale Bait, clearly. But I have no idea what that means.
The site in question:
I figured the odds were at least 50/50 that they do some form of lawn care, tree work, landscaping, etc. But if it was advertised on the side of the pick-up truck, I didn’t notice. On the other hand, they were parked on the side of the road, in a place where I didn’t have any attention to spare for reading the sides of pick ups.
Or might be into eating acorns; or be a producer or seller of acorn flour. Considerable preparation’s necessary, but there’s a lot of nutrition there.
Saw some tortured variation of RESIST this morning. I couldn’t get a good enough look at it to tell what the exact “spelling” was.
IDRAWU
No clues from my angle whether that’s professionally or just a friendly warning