Can Trailer Axle Spring Seats be Relocated If Needed

I currently have a custom triple axle trailer that I want to replace all 3 axles with new ones. The current measurement is 80inch HF and 68inch SC and rated at 6K. If replace with part #8327826, can I weld on new spring seats at 68inch without messing up the integrity of the axle? Also, any issues with having a wider stance by 3inch on each side? This is a custom boat trailer. I want to either weld on new spring seats at 68inch on the axle OR relocate the the hangers to 71-1/2inch on the frame. Welding on new spring seats seems to be the easier route. I can relocate the spring hangers as there is enough room under the I-beam frame, but i would have to reinforce the frame at the mounting location as the new location would be under the I-beam flange instead of the dead center. This seems like a longer term solution, especially when purchasing new axles, but more work up front and more required time that I currently do not have. Also, my current setup as 4-Leaf springs at 26. Is there any issue moving up to 6-Leaf springs rated at 6K measuring 26? Thank you!

asked by: Hubert