dust proofing your <span class="highlight">caravan</span>

Looks a bit of a problem. How would a pressure hatch in the top go? Commonly used in Caravans to scoop air into the van through a forward facing hatch in the roof. This pressurises the van and keeps dust out. Mightn't work as yours is low line and dust may get up over the top and ito the hatch anyhow???

Try 100mph/duct tape............. shouldn't come off when travelling.

Remembering of course that is illegal to cover the vent in the bottom of the door

Which is the safety for an LPG leak

Where is the dust mostly getting in Tawnsey?

We had and old wind up camper and dust poured in through the four seasons roof vent, and through the seams around the wheel arches. Gathering the bed covers and shaking outside than a good sweep was the simple way.

Very little dust gets in our present caravan, and I have ways of blocking most.

This is how I dust proofed my 2002 Jayco OB Finch with pros and cons 11 months after install.
http://www.myswag.org/index.php?topic=42387.msg705072#msg705072
Cheers

Our Penguin is now pretty good, but aside from the obvious door and fridge vents, the major dust inlets were gaps in the metal wheel arches and the hole in the woodwork at the back of the fridge for the wiring to run under the bed to the battery and "charger". For the wheel arches, I just used silicon to seal all the open seams. For the hole for the wiring, duct tape stopped the dust getting into the underbed space. I don't normally block the fridge vents as we run the fridge on 12v while travelling; this means an occasional removal of the bottom vent is required to vacuum out the space. There are a number of solutions to covering the door vent, but as others have advised, you must remove the cover in order to be protected from a gas leak.