Completely agree. You will want a foam board plug for the escape hatch if you use the camper in the winter. Otherwise condensation will form on the cover and it will rain on you. You do need the fan for circulation PLUS a second fan as Les stated over the sleeping area. This is key to comfort in high heat areas. I use a large 8" brushless DC fan over the bed blowing on me. You could also locate the Fantastic fan over the bed. There are no energy efficient air conditioners for off grid mobile use. You would need a generator for that.Diplostat;
yes the hatch lets in sun,but the shade blocks it just fine,if you were really worried it
would be easy to add a piece if foam insulation board to hatch,we have a powered vent in place of ac unit
and also use a clamp on 12v fan in the overhead bed/hatch area.
remember we live in the so. calif desert so we deal with heat all the time,no problem.
hope i'm not highjacking this thread but i think it pertains to op questions.