If you want, try shooting in A Mode.
Maybe you can try to open up your aperture to f8 or f11, that can drive down the shutter speed to less than 6". Do an Exposure Compenstaion of +0.7 to +1.0 or more. Then cover the viewfinder, that can further reduce the shutter speed. Maybe you can try out my work flow:
1. Set the White Balance using some green grasses or plants with the IR Filter ON
2. Ensure that Custom White Balance is set properly then remove the IR filter
3. Exposure Compensation set to +0.7 or +1.0 or more (depending on condition)
4. Set to Aperture Priority Mode using F8
5. Try shooting in the opposite direction of the sun
6. Compose the shot first, then switch Focusing to Manual (Camera on Tripod)
7. Put on IR Filter and lens hood to prevent flare
8. Cover viewfinder and trigger the shutter release
9. Do Pro-processing