Underslung battery tray mounts. - van converters.

ive seen a couple of options for underslung battery trays for VW vans but i don't see much out there for others.

https://www.newwavecustomconversions.co.uk/product/under-body-leisure-battery-storage/

Ive an NV400 with a deep area between the monocoque chassis rails and I've got 2 x 110ah leisure batteries that take up alot of space inside - and it came to mind last night when i was lining them up I've a lot to gain by getting them outside.  

Really don't want to do a sunk floor mainly as my floors finished inside. 

Has anyone seen a box that could be mounted to the chassis rail or the floor pan but can hinge or drop down to allow access to the batteries from under the van - or do i even need to enclose them - is there any harm to just making shelves on either side and clamping the bare battery to them - like they do on certain trucks in warmer climes. 

Batteries are maintained by fixed install solar year round I'm not super concerned about the cold but would probably insulate them manually for events like the puffer. 

Thoughts - or reasons why this is a bad idea , Usually there is a reason why you cant buy these things - small vans excepted because they are too small people will put up with bad ideas to create space.