LED Lighting For Subways

I'm getting ready to LED my R40 Slant subway set. I did my R32 set already and while it looks great, there's a few issues I hope to fix. The first and biggest is running them on DC. Currently, I just run my LEDs on AC while it works well, they do give off (at least IMO) a bit more heat then they should, on two of the four cars, the shells are developing little indents due to the heat. No fun. I do NOT want that to happen to my R40. I'd like to keep the flickering on the cars since the real cars flicker over switches and the like. I'd use @gunrunnerjohn's lighting board since I run DCS but would there be a way to remove the capacitor (or install a smaller one) so the flicker will stay? The next issue is when I did the end lights in the powered car, when stopped, they do dim a very slight bit, not enough that you could really tell but if you look at it directly after it stops, you can see the change. Almost like the car has rule 17 lighting. I run the set at 18v but if I turn the voltage down a hair (to 17v) that goes away. Thanks for the help.