Scrim or trace is good over LED panel lights, even just to get rid of the fringes in the shadows. For softening the light source the further away from the light source you hang the diffuser the better, because it makes the apparent light source bigger and therefore softer, even a few inches makes a difference.
My 'fits-in-the-carry-on-luggage' 3 point interview set up is this: I have a LED key (a flexible LED panel - really recommended for doco work) and a couple of strips of card that I tape to it that hold the scrim out 10cm or so from the panel, it works well as a small soft key light for interviews. For fill I usually use a folding circular reflector, and if needs be I aim another LED panel at it. Then I also have a small DedoLight spot which I use as a rim or 'hair' light or to add spots or slashes of light to the BG.
Also remember to look for natural lighting. It can be problematic, like when there is bright sun outside and a dark interior, but if you use windows and practical lights as sources intelligently and then augment with what you have in the kit you can get good results with less gear, and you get a more verité look than a Hollywood style lighting setup.
As CoinRocket said, bouncing is better, but generally LEDs don't give you enough grunt to be any use as a key light when bounced. A 1.2K HMI is an order of magnitude brighter than a battery powered LED.
There also inflatable softboxes that win as far as portability goes. I haven't used them but I've seen good reviews.