There's no way ull be able to run 1000w with no hood without having temps in the 90s unless u wanna ruun ac all the time.
I would recommend you go with 2 400w set ups like said above. Better coverage and less heat. I would recommend running ceramic metal halide bulbs. U can use them for both veg n flower and u can use them in open hood because they burn much cooler. Ii had a reg 400w mh in my 4x2x8 and temps gott upto 85, once I put in the ceramic metal halide the temps haven't gone over 78 since and the bulbs 9 inches from canopy in an open hood. Only a 170cfm exhaust fan and that's it.
I would recommend you go with 2 400w set ups like said above. Better coverage and less heat. I would recommend running ceramic metal halide bulbs. U can use them for both veg n flower and u can use them in open hood because they burn much cooler. Ii had a reg 400w mh in my 4x2x8 and temps gott upto 85, once I put in the ceramic metal halide the temps haven't gone over 78 since and the bulbs 9 inches from canopy in an open hood. Only a 170cfm exhaust fan and that's it.