Situation
ISAF Regulation 20.3 Competitor's Advertising defines permitted competitor advertising. Regulation 20.3.1 addresses advertising on Personal Equipment, and Regulation 20.3.2 addresses advertising on boats.
Regulation 20.3.2 permits class rules to limit advertising on boats. No such limitations are mentioned in Regulation 20.3.1. A one-design class rule states that advertising is restricted to hulls only.

Question
Does this class rule restrict advertising on personal equipment, or does Regulation 20.3.1 always permit advertising on personal equipment?

Answer
A class rule can not restrict advertising on personal equipment.

Personal equipment and boat are in bold type in regulations 20.3.1 and 20.3.2. According to Regulation 20.1.3, this means that the terms are used as defined in the Equipment Rules of
Sailing:

Personal equipment is defined in ERS C 5.3.
Boat is defined in ERS C 6.1 and it specifically excludes personal equipment.
Regulations 20.3.2 and 20.5.1 permit class rules to limit advertising on a boat.
Regulation 20.3.1 always permits advertising on personal equipment, chosen by the competitor with the agreement of the person in charge, except that bibs provided by the Organizing Authority shall be worn as detailed in Regulation 20.4.