The 2nd person pronouns bo and boso can be used for any addressee, without politeness implications. Nonetheless, politeness may be expressed by addressing a person as Señor/Señora (as indicated by Goilo 1972: 35), or, more commonly as Shon (literally: 'Mister/Mrs.') – a form which is not gendered. In the example Shon warda kurpa, the addressee is a young girl, addressed by an old man, showing that Shon is truly a politeness marker. Also, forms such as mai ('mum'), pai ('dad'), and other kinship terms and the addressee's name can be used in place of pronoun bo in addressing the relevant person. Persons in certain professions may be addressed by their professional title, e.g. dòkter 'doctor'.
I have classified this system as involving avoidance of 2nd person pronouns, but the frequency of this usage has not been investigated, and is probably highly context dependent.
Source: Maurer 1988a: 394
Source: Joubert 2002: 292
Source: Birmingham 1970: 64