The bumper is fairly easy to install if you have the right parts. As was already said the jdm metal bumper support under the urethane shell is thin but complex, it has provisions for holding the fog lights also. Fabrication of it would be difficult even if you had a shop.
There also two right angle jdm brackets that replace the the USA bumper support brackets . You could fabricate those but it would require a lot of fixturing to get the bumper positioned and then measure for the brackets. Get the jdm brackets if you can and save a lot of work or just one to use as a pattern. They are mirror image parts.
You will have to drill two holes on each side of the frame to mount the JDM angle brackets. There are two half punched out holes on the outside of the frame where the USA bumper brackets mount. I found the ideal place to drill for my jdm bumper was about 1/4 in above the half punched out holes. I drilled right on the half punched out holes and had to slot the holes in the angle brackets to move the bumper upward the 1/4 inch.
The chrome USA trim strip could be reused if you can get it off the USA bumper without cracking the clear overcoat on it. The adhesive makes it very tough to do this.