Strange that you have an issue with the battery width, usually the length is the issue with the SC series lights that have the pins instead of springs, in particular, batteries with a protection circuit. There are quite a few threads on here discussing that aspect of the SC63. Do you batteries have stickers on the battery wrap? I suggest taking the sticker off your batteries. I have a Fenix brand 18650 that fits snug in there because of their sticker label adds a bit of thickness that makes it fit very snug (i have to use inertia to get it out). My SC63 fits most of my 18650s even the salvage batteries. Protected 18650s are a little longer, but i don't have too many of those and avoided their use in that light (and the SC64 now).
I really like my PFlexPro L2P. It has a moonlight mode option. It has 22 mode options that you can pick from. It may be bigger than your SC63, I don't know because I have never seen one. It is slightly longer than my Malkoff MD2 or Surefire G2X Pro. Very versatile light though. Nice beam, tint options, reflector choices, etc. The Malkoff AA MDC has a similar low mode, but obviously not 18650 compatible, but much smaller size.
Malkoff MD2 or MDX, Surefire C2, 6P, etc., Solarforce L2P are a whole different class of light than the Zebralight 18650 lights. No comparison on size. Don't get me wrong, i've been finding myself carrying a P60 format light in a holster and love it even though it is much heavier, longer, etc. Still, I really like having the drop-in flexibility, although even my Vinh quad has a hard time matching the brightness of the Zebralights, especially the newer H600 headlamps.
Back on OP, you might try a Olight S2, they are a little longer than the SC63 (or even the SC62) and have a moonlight mode although only one and its isn't as low as the Zebralight SC series.
Perhaps get an SC62? They have the same UI as the SC63 and fit longer batteries because they have springs instead of the pins. The width is pretty much the same though, although i don't remember it having issues with the batteries with the stiickers..
Have you considered the headlamps instead? The H600 series use springs and can fit a longer battery. The new ones also have the new programmable UI as well.