Now .. fuel gives me an error on the last line of code .. that 1 isn't a valid field. That's weird .. because this is actually working MYSQL syntax, and saves me a where clause on the join.
You have never been able to pass literals. It expects a field name there, and will escape it for security reasons, which means 1 will become `1`, which fails.
You have to encapsulate it in a DB::expr(), to avoid it being escaped: