245/65/17 is a popular swamper size that's about as big as you'll get on the van without (much) rubbing.
Swapping to this from a standard 215/60/17 tyre will lift the van 30mm anyway without the need for a lift kit. However, be warned as the speedo will under read and the larger diameter will essentially lower the gearing , making the van slower to accelerate and labour more under load.