how rusty is too rusty?

So, Paul and I have decided to purchase a VW T2 Bay Window Campervan. Paul travelled to Portugal, Spain, France and Amsterdam for three months in one several years ago and loved it. He has since regretted it's demise and, as we are getting married next year, we thought that a trip through Western Europe in a VW camper would be the most perfect honeymoon.

I have read a (little) bit online and have concluded that I would be perfectly capable of completely rebuilding the interior of the van myself, with perhaps some help from Paul. I have found step-by-step guides to treating and laying a floor, and building a fold-down bed (which I now know, in VW terms is called a rock'n'roll bed - a good name I think for what is essentially a sofabed!).

This just leaves all the rest to consider when we buy our van.  Paul is confident that he will be able to do a lot of the work himself (from a manual). So, do we go for an eye-wateringly priced vehicle that won't need too many parts replacing or too much welding back together, or go for a rust bucket that barely resembles a van, never mind a something we might live in for a significant length of time?

I have reasonably strong feelings about the colour of the paintwork, and both Paul and I are now certain that a complete re-spray going to be necessary. Consequently I resent the idea of spending money on a van that already has a decent paint job in the wrong colour.

In reality it seems the best option for us is going to be spending a smaller sum on a restoration project, and doing as much work ourselves as we can. So the adventure starts - we are now trawling Ebay, preloved and gumtree to find our perfect van. Watch this space for details of the grand purchase.