VW Caddy... your going to be struggling with space so forget a TM...
Any one of the three machines mentioned in the previous post will operate on your van but just remember...
You will need to carry extra solution and vacuum hoses in order to van mount the porty, i would carry 125' at all times to be safe, unless you have a fresh water tank (minimum its going to have to be 125lt) you will need to carry a good quality hose pipe to feed a constant supply to your porty if it has auto fill.
The waste water ideally needs to be auto pumped out so your not putting your tools down every 10 mins to check the van isnt flooded due to rising water levels!
Lots of things to consider here...
Or you could simply buy a ramp... i bought my Sealey one from Ebay and it cost me £200.
I now always remove my Jag from the van, it allows me to check water levels, reduces the chances of flooding your van, keeps the machine cooler, increased performance with shorter hoses..and reduces the amount of hoses i need to carry.
Check the weights of each machine mentioned... very important