A water hose timer (Sprinkler timer) before the R/0 can be set to run enough once a day or two filling a main reservoir.
This reservoir can be located near a drain to which an overflow can be plumbed.
If a switch type of ATO is used, the top-off pump can be placed in the reservoir.
If a simple float valve is used, the reservoir pump can pump up to a second, smaller reservoir which is gravity feeding the sump controlled by a simple float valve.
This is similar to my setup. After a few floods (usually from leaving the R/O supply on), I feel better with the overflow even though it has never been used.
The washing machine trays that Lowes sells, or something similar, are a nice backup for sumps and other potentially overflowing containers.
Backup plans are the way to go!
BTW, those "push loc fittings" haven't failed me yet. But don't forget about Murphy's Law!