The commissioner shall have the authority to appoint no more than three deputy commissioners who shall serve at his pleasure, and to define their duties. The deputy commissioners shall be persons of good character, of good business, educational or administrative experience, shall have no financial interest in any partnership, corporation or association with which the department has any financial dealings and shall devote their full time to their official position and shall have no other lucrative position while serving as such. Their salaries shall be set by the commissioner but shall not exceed the salary paid the commissioner.