Crawl space under a 14 x 15 home office. Block walls with 2 x 12 joist Insulated with 6-8 bat insulation and a staple up radiant hot water heating.

Two questions:

Insulation: When cold <20 degrees F the set temp is 8-10 degrees below actual temp in the room, I am concerned that more insulation is required but I need the room under the floor between the insulation and sub-floor for the warm air pocket with the radiant heat system, suggestions?

Dehumidifier: Most dehumidifiers state for above 42 degrees F, this space can get cold, any suggestions for a unit, or option to use for a dehumidifier?

Thanks Stan K