Yes you can, Piko do a 5amp remote controller, you can use your existing controller to power it, set it at 20v , do you have a voltmeter? always a handy device, the receiver would need to be mounted in a box of some sort if using outdoors, however the receiver can be indoors with a lead going to the track. The transmitter you just carry with you. your existing controller is only 1 amp so eventually you would need a 5amp supply giving you 20v dc
Piko 35040 R/C transmitter and receiver. Try Garden Railways Ltd £72.00