Fibreglass Insulation in Basement of 1920's Maisonette

[Rowie007]

I recently purchased a 1920's ground floor maisonette with a suspended floor, under the house there is a void of about 150cm (considerably less towards the front of the house). There are steps leading down to the void from inside the house, and the space is heavily used for storage. There is also a large number of wires and pipes down there doing I don't know what - I suspect many are leftovers from multiple renovations but can't say for certain.

I want to insulate the floor, and was thinking of using 170mm fibreglass rolls. My concern is what to do about the exposed bottom of the insulation. Because the void is frequently accessed, I don't want fibreglass fibres getting into everything. Am I able to cover the insulation when I've installed it? If so with what? I don't want to risk rot, and many of the posts I have read warn me to make sure the space is properly ventilated.