I also grew up poor and in the country. I helped in the house. My brothers, outside. In those days housework was considered "woman's work." My brothers should have done some housework. They're in their 40's and 50's and are terrible housekeepers. I know that housekeeping isn't considered fun by many people but I learned to like it. I felt really good to have finished something.
I also read and read. I finished a book a night for awhile in junior high. He could find ideas for activities in books and on the Internet.
He could have projects, such as refinishing a piece of furniture, washing the windows, of course keeping his room reasonably neat. However, I do believe that a kid's room is their room and they can be sloppy as long as it isn't a danger to "public health."
At around that age I collected stamps. I ordered large envelopes of stamps and went thru them looking for specific ones shown in a book. The book was like a current day stamp book in that you glued the stamp over the picture. I think you could find both book and stamps at a hobby store or over the Internet. Stamp collecting was really inexpensive in my day.
There are other hobbies he could pursue at home. My brothers used their allowance to build model planes. My cousins built a very basic radio system. Again inexpensive. My brothers also worked with leather. It is more expensive but not too bad. At least back then.
Wood carving is another hobby. Your local hobby store could help him get started.
I know Grants Pass from my childhood. Is it now not safe for kids to ride their bikes around the neighborhood, to a friends house or to the library, etc?
I would think that Grants Pass is large enough to have a kid's club of some sort where kids can play basketball, swim, box and other activities while supervised by adults. How about Big Brothers?
Our family was active in church and all of us kids were in a youth group. There is 4H with projectgs for city kids. A Boys Scouts group that is for older kids and has a different name.
He could learn a skill or just have fun thru Parks and Recreation classes. At least I think Grants Pass would also have an organization of that type.
Does he go to friends' homes and/or have his friends come to your house? This is an opportunity for the boys to be creative in finding a way to entertain themselves. Of course, parents must know and approve what they are doing. :):):
By the way, all kids this age are bored even when they're involved in activities.