If you have a windshield or 1/4 to 1/2 windshield take them off for the summer & let the air blow through the cab.

 

My two cents. I had the same problem.

I removed both the front and rear windshields, then I went to Lowes and purchased some of that metal foil take that they use for heat and AC and a sheet of double foiled backed 1/2" insulation board. I completely covered all areas under the seat especially around the seat belt connections with foil tape. Then I purchased a vehicle window shade at Walmart that has foil reflective coating on both sides of the bubble wrap. I covered all area under the seat being carefull to leave cut out for the seats to sit flat on the brackets so the seat will still secure all the way down. Then cut the 1/2" foil backed insulation to fit behind the seats(the seats will hold it in place. I also took and old wool " fire" blanket and placed it between the back and the seats and folded it around the seat belts in the center. Almost like forming a pocket in the center for a water bottle to stay cool. In addition to this, I also cut 1" holes across the top edge of the rear trunk compartment to allow hot air to rise straight up from the motor. This has worked out awsome for me. No more burning legs..

Hope this helps.

 

Drop the skid plate and header wrap the coolant lines, then spray foam the inside the tunnel.

 

Or maybe just by the kit from wolfsnout! Works great!

 

Wolfsnout does not make anything for XP900, just newer model 900.