I'm not really sure why GW didn't do this themselves, but a simple way of adding more fortifications to your lists would be to simply assign points and size limits to the battlefield debris section, making them purchasable fortifications for your army lists in friendly games.

For example:
Barricades: bought as a 18" length of barricades, divided into three 6" sections which may be deployed separately. Confers a 4+ cover save. each section up to 6" may be targeted separately, counts as an armour 9 vehicle with 2 hull points and is destroyed on a penetrating hit. 40 points.
I'll compile all the final consensus in this post (when I'm not on my phone)

So post up your favourite "Battlefield Debris" from the rulebook, its limits/rules (size, length, anything relevant), options, and points.

Feel free to modify anyone else's posts, (if you disagree with the points cost etc) including and especially mine

And I'll compile over time.

TSINI