No one can tell by looking what brand sealant it is. Not even the pros that do it for a living. The trailer mfg may change brands in the same year so only they could tell you what they used on the trailer
Dicor verticle for the sides or Dicor self leveling for the roof.
Proflex is one of the more popular seam sealer.
Sikaflex is another popular sealant.
Do a google on the subject and then a you tube. Lots of ideas and helpful info out here.
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
'97 Park Avanue 28' 5er 11200 two slides