ibc is 1000ltr secured to floor with 4x4" eye bolts thru the floor with 4" plates above & below the floor,
the tank is fastened to these with2x 5 ton braking strain ratchet straps from the railways,i no a man lol.
the other water is in barrels that fit the freedomtrolley strapped to the tank, if i need more water for schools etc i will put a 200ltr barrel in & strap it to the tank,with 2 straps.
baffled no
i had the same tank in the other transit un baffled
dident find any problems with water sloshing as most of my work is within a 5 mile radiuos so most of the day the van is parked up in same street or village
not saying that it cant be a problem ( just saying that i aint found it to be)