UK driving licence categories in the US

[MaximumJed]

We're considering touring around the US, in either a fifth wheel camper or maybe an RV with a toad. Unfortunately, I passed my driving test in 1998 and, while I've done a B+E extension test, I can still only drive up to 3,500kg GVW vehicles in the UK.

Does anyone know how this maps to the US? If I want to drive anything bigger than an F150 will I need to get a C1+E before we go over? I appreciate I probably need to speak to a legal bod in the US and each state probably has different rules - just wondering if anyone already has experience of this.