Had some time yesterday so I made up some extra support brackets for the blade mounts as e2q suggested. Keep in mind that these brackets are constructed from “on hand” materials. That’s what I try to do before going out and buying new stuff. I like to use up the old stuff left over from other projects first if I can.
The front hitch plates where the plow mounts hang down from the front of the frame and would take all the force when the blade is pushing, or is bumped against something. As e2q suggested they do appear to need reinforcing to help prevent potential bending from blade impacts.
There is a spot on both sides of the frame a couple of feet back that has 2 holes that seemed a good place for the brace. These holes are empty on the left side but are used on the right side to mount the handle support bracket, but the brace can be mounted under this bracket.
Also the left side bracket had to be bent inboard, under the frame to allow clearance for the tire when turning left. The right side bracket could be straight and not interfere with the tire.
Here is a photo of the left side bracket. The blue arrow points to the area of the bracket that needed to be bent inboard to provide clearance for the tire when turning left. Green arrow is where the bracket mounts to the existing holes in the frame. The red arrow shows the front hitch plate that needs reinforcing. The left bracket also needed to be low enough to avoid interference with the steering arm (yellow arrow).
This is the right side bracket. Blue arrow shows the bracket. Green is where the bracket mounts to the frame under the handle support. Red is the hitch plate.
Thanks to e2q for making the suggestion. I am hoping this will help to avoid any problems with potential frame bending.
Some additional photos from the project...