There are a few basic ways to age white rum
1/ store it in a container about 3/4 full and give it regular attention - remove the stopper and agitate/shake as often as practical. Keep it warm to speed up the process.
2/ same effect as above but accelerated by using an air pump with a diffuser - eg an aquarium pump with a S/S aerator. - You can also combine 1/ and 2/ obviously. Run the air pump for a few hours every second day - take a sample beforehand and compare with the aerated product as time goes on. When I do it I use a copper tube embedded in a conical RTV silicone stopper moulded in a plastic funnel - suits any size container neck and the mass keeps a decent seal but still allows the pumped air to be expelled. Mark the level of the product on the container before starting (if possible) and keep an eye on losses as pumping will increase evaporation losses. Be aware also that pumping can strip some flavour - Overall though it's a very valuable smoothing technique
3/ Age on old oak and charcoal filter to remove colour - this approach will smooth the product but also trim the flavour. If you use old oak you can also leave on just long enough to form gold rum which is a good balance between white and dark, then remove the oak and leave it for a further period if needed.
In terms of ABV - I'd leave it at cask strength as the reactions will occur more rapidly than those at bottle strength. If not on oak, you could also leave it at still strength but your evaporation losses will be higher.
Experiment, experiment, observe, observe ..have fun
