Benefits to both solutions, static and van mounted RO.
We have a static, with 2 x 1000l IBC's in a garage, using a submersible pump to deliver to the vans.
I like this because it means I dont have to have 2 RO set ups (1 in each van), and I can monitor water quality without being halfway through a job, realising a filter or my resin is shot, and having to stop a days work.
Also the system is less likely to get damaged in the garage, as I employ, there is a likliehood it would pick up damage if it were all in the van!
If you had a van mounted RO, then, for you, as a single operator, with no real plans to employ, then you are more likely to take care of it, and monitor quality etc, so no risk of damage. You can also simply plug your hose into the van, and leave it filling up overnight.
Saying that, if there are any issues, and you are not filled up for the days work, you could be in trouble.
In a garage your RO is away from frost, so cant get damaged, wheras unless your van is insulated or you heat it every night, it may freeze up and crack...
A static system has a little expense, such as transfer pump and hose and an IBC, but its easy to leave your IBC filling up when you are out, come home, fill it up, and be safe in the knowledge you are ready for work the following day.
Lots of variables as you can see!