The ghetto solution is to cut the bottom of the brake light red cover off so some of the light spills over the plate. You get extra credit if you cover the missing red plastic with something transparent. The mid range solution is to use illuminated bolt heads, but the ones I've seen are like $30 for a pair. The primo way is to get a dedicated illuminated plate holder.
Cops here aren't likely to ticket for lack of light but safety inspectors will stop renewal if they notice it, and the cops will certainly pull you over if the sticker is out of date. But my bike is new enough I haven't had to reinspect this year, so I have a whole nuther year to procrastinate.