Funnily enough I have today had to insure a second van with LV today but initially was told that they could not insure me due to the number of changes!
I then phoned and spoke to them and told them that the vehicle was nearly identical to the first van that i have insured with them. The only difference was that this one is LWB and has "interior changes" and "pop top".
Initially they maintained that that they couldn't do it, but I persisted and managed to establish that when I obtained the original online quote, I had ticked "Other" in the list of changes. This makes the vehicle uninsurable! I had ticked "Other" because "Pop Top" was not an option on their list of changes!
It turns out that I needed to leave "Other" unticked and choose "Sunroof" for the pop top.
This was sorted over the phone and their quote was very competitive.