Since it sounds like you are going to have a more permanent type shooting range, as I do. This is what I made. I used some old left over deck posts. And then some ruff cut cedar boards, a friend ran out on his saw mill from my trees. I also mounted castors on the feet so I could push this around when necessary. I wish I had now ran a small simple straight axle and put larger wheels on the feet as it would have made the bench not bog down in the soft grass and dirt...
the simple bench seat locks to the leg and can be removed. I adjust the height by simple boards under the foot. This way anyone can use the bench no matter their height. The shelf under the main table holds the home made shooting rest.
So far this works great for me. It doubles as a fish cleaning table, and work in the garden table when I have to clean vegetables... Since I can move it all over, I move the table instead of the target since I shoot into a steel bullet trap...