When assembling a Jobsite Series 6′ Baker (I-CISC) and its 39″ extension (I-ISEX4PPNCAS), do we have to install a guardrail (I-CISGRJP)?

Can we stack Jobsite Series 6′ Baker (I-CISC)?

Can I leave the guardrail’s (I-CISGRJP, I-CAISCGR, I-BMSGRJP) doors open?