Depends on if they have proper risk transfer and certificate tracking processes. Work Comp for the supervisors should be doable but they want to ensure they are not taking on subcontractor exposure. The GL is extremely important to making sure their sub agreement and insurance policy subcontractor conditions form is in compliance and there is no CG 22 94 exclusion.
PEO - unfortunately no standard carrier. It really depends whether or not the GC has payroll or not.