I would recommend fiberglass blown in insulation rather than cellulose because it is not conducive to insects.
Attic walkway over insulation.
Walk to one end of the attic by carefully stepping only on the wooden ceiling joists.
Ensure that the end of the first plywood sheet lands on a piece of 2x leaving enough room to position the.
The blown in insulation can be blown right over the ductwork.
A common misconception is that it takes little more than the installation of some decking over the attic joists to ready an attic for move in.
Exposed floor joists can cause condensation on the inside of the ceiling peeling paint and nail rusting.
Because of this the space is able to supporting heavy loads.
Place a 2 inch by 3 inch board directly on top of the joist nearest to the edge of the attic with its largest.
Place the first plywood sheet on top of the 2x structure starting by the attic entrance.
The attic walkway is constructed so that sits above the horizontal chords of your attic.
This is because the horizontal chords are the strongest part of the attic.
You could also lightly spray for insects over fiberglass if needed.
If you can make the walkway 2 wide it most likely would not be necessary.
However if you need to make it narrower i would recommend standing some unfaced blanket insulation on end along the edges of the walkway to hold the loose.
The trail you leave in the attic can easily end up tracing a path on the ceiling below.
The floor must extend beyond the insulation so that the insulation is properly covered.
In some houses this may be the case.
In many others.