VW trikes have the most limited luggage space of most vehicles. A top box and some just strap their overnight bags onto their side ladder bars. I
found a cheap solution and I cant see why Beetle owners or sedan/Fastie owners cant use these either.
Firstly you attend a Autobahn store or simialr and purchase these items:

Top left is a step used by 4WD owners that slips over the wheel to allow you to get stuff off the car roof. You buy some 10mm tube for the rack
floor.
Buy a bicycle tow ball rack. The type you need is the one that clamps onto the tox ball then as a secondary clamp there is a knob that you turn.

This clamping system is foolproof. I weigh a hefty 125 kgms and it wont budge.
You might have to cut down the height of the clamp rods. I had to so as to get the unit not to hit my top box. Here is the unit clamped onot the tow
ball

I made it so it folds up.

Perhaps Beetle owners could make it so luggage can be stowed on each side of the unit forward and aft?

We can take a really large sports bag, enough for a few days, onto the rack.

Total cost $120. You might need a rego plate.
nice work there mate, thinking outside the box
Cool, but you can't tow the van with that on, or maybe you could put your stuff in the van. 
Actually you're right but when towing the van it isnt required. A quick trip interstate and we take the rack and sports bag.
Anywhere a towball is placed the rack can attach to. eg a draw bar etc. So it can be vertatile.
Great work...
when I go into hardware shop and they ask Me what I want
I can't tell them as I don't know until I see it and can make it do something its not designed for...lol
You did some great thinking there... lol
the extra number plates are illegal in NSW
even though many people get them made to put on bike racks..
I can't see how that stays upright just on a tow ball???
LEE
the clamping grips onto the tow ball and under it surrounding the stem of the ball itself preventing movement.