You can also use a resistor between the regulator's input and output to supply some of the current, thus reducing the power dissipated by the reguator. Just be careful to maintain a minimum load on the regulator's output so that the regulator does not go out of regulation.
if the space, heatsink etc are a problem, you can roll your own regulator that is anything you want it to be. specially if you need volume. you can easily make something that drops in place oif existing circuit with whatever pinout you need.
but existing crop of SMPS is simple to use with only few external components and the whole thing takes very little space, even for significant load current. many have built in switching transistor etc. so 3-4 external components will do.
You could try reviewing the circuits to see if you can reduce the current being drawn. Resistor values are often just pulled out of the air (or a warmer darker place) and not based on what is really necessary.