Ideas for low maintenance bike/ powerwheels path

So I want to build a path in the back yard that my kid can ride his strider bike or power wheel on that won't take a lot of maintenance.

I was leaning away from dirt cause keeping weeds off seems like a pain and gravel cause falling on gravel sucks.

Playground matting. Seems Expensive

Any suggestions?

Is there any hill to your back yard?  Balance bike on a grass slope is great!  

I got my daughter a balance for 3rd birthday.  She was only mildly interested in it right away but her interest grew.  When she was 4yr3mo old, that Christmas, I got her a sled.  We have enough slope out back to ride a sled right here at home...but that Christmas was unseasonably warm so no snow.  She was excited about the idea of sledding and asked, "can I take the balance bike down the hill?"  My answer was, "well you do have a helmet!"  I was super happy that she wanted to try that.  We never had before.  

4yr3 mo and it was her idea!:

All the rest of that winter (and there was little to no snow that winter)  I had her going down the slope of the fairway out back.  Soft, smooth, short grass so falling didn't hurt and fully clothed made it even better.
This 4yr6mo

That spring, it was time for pedals.  For me, the secret was to get her a pedal bike that was the exact size of the green balance bike. The reason being that she would feel safe to just put her feet down any time.  I knew a bike like this would be outgrown quickly so I went used.  On FB, locally I found a Princess bike for $15 but no training wheel...we wouldn't need them. This video is taken about 20 minutes after she first received this pedal bike. A few falls in that 20 minutes, but...
This is 4yr8mo:

In reply to John Welsh :

It is fairly flat. A little bit of a slope.

If you use it enough the grass and weeds won't grow on that track.   But the mud might.