Hunterjeff,
Please provide pictures and/or further explain your comment of "uncovered connection". Based on ESA (Electrical Safety Authority) rules, ALL wire connections must be within a proper electrical certified box. Especially on a Trailer - that endures lots of road vibrations and/or folks putting their hands into storage compartments - where the open connection exists. Hoping your can provide a picture - to give us a visual.
If you are talking about a "portable" Surge Protector unit that push together type connectors, then yes. They don't need to be inside a box. If outside in the rain, I wrap a plastic bag around my connections - then wrap duct tape around the plastic bag outer wrapping. Probably isn't needed but IMO, all electrical connections should be kept dry. Especially if my feet on our damp ground and the connectors are in my hands - when connecting or disconnecting them from Service Post.