Just because you can, as the builder, "adjust" your gross weight it doesn't make doing it a good idea.

Remember these points:

WHEN the wings come off they break at the root.
Increases in gross weight invariably happen in the fuselage.
The original gross weight for the IV was 2,900 pounds.
Only 1 wing was tested over 10 years ago. Are you sure nothing has changed since then??

Before you do a ratiometric scaling of the gross weight based on decreasing the factor of safety from 2.0 to 1.5 you MUST subtract the weight of the wings AND the fuel in them. This totals about 950 pounds. Add the weight back after scaling. You also need to use the original design gross of 2,900 pounds.

I keep hearing stories of higher and higher gross weights and am invariably reminded of the Tacoma Narrows Bridge.

It is a REALLY BAD IDEA to overload your airplane. Putting a 3,800 pound gross on the data plate will keep you legal but WILL NOT keep you alive.

Regards
Brent Regan