There is nothing in window manager tweaks that deals with Window Resize.
This issue stems directly from how XFWM4 manages window borders combined with the current (poor, in my opinion) trend in making borders 1 pixel in size.
1 pixel is not enough of a grab area.
In .css, the border margins can be extended to create an invisible border area to grab, allowing themers to make a 1px sized border with a 10px grab area.
In XFWM4, I solve this problem simply, by creating larger window borders by matching the background color into a portion of the border with the 1px colored boarder that was in the original theme.
Recently, I made a Cinnamon D.E. version of the Zorin themes called Zenith including Metacity Window Borders.
This thread may inspire me to expand that to Zenith with XFCE, that includes large grab areas.