A mobile booth system, carried by a truck or like mobile vehicle, creates a portable, temporary in situ booth or enclosure at a remote location. A pair of side by side slide assemblies are formed by respective nests of C-channels and I-beams, each assembly extending and retracting through an opening in a sidewall of the truck wherein to deploy and retract a roof section outwardly from the truck. The roof section is deployed through a dedicated opening in the sidewall, which opening may be closed by a closure panel but opened by deployment of the roof section. When deployed, an enclosure is formed by attaching a drop cloth to the roof section. The enclosure when used as a paint booth enables rapid deployment of a drop cloth about irregular or difficult surfaces to be painted, as well as to contain overspray and fumes created by the spraying operation.