I'm with Alexander Swan. Not had a problem. 500 litre bolted down DIY fitted delivery tank with tools cover in a locked van, & a Reach & Wash vehicle on my drive within a couple of days if I have an accident and my van is off the road.
Without getting into a debate about whether ratcheted tanks are loads & whether bolted tanks are modified vehicles, I have to say that personally I like to be honest with my insurer & have piece of mind that I am covered.
Yes you'll find cheaper cover, maybe even with a low excess but I can sleep at night knowing I've been totally honest & if I have an accident I've done everything reasonably possible to hopefully get paid out and/or not sued.
Divide the expenses deductible premium by 52 weeks of the year and it's about the cost of one domestic house a week. Not bad I think.
Wfp is still relatively new and until insurers decide what is & isn't regarded as a load or modification I think we have limited options unless your willing to take a chance. Personally I'm not.