Disabling Mipmaps for realtime Reflection Probes?

Hello, I'm utilizing Reflection Probes to simulate wet roads with crisp reflections, and the effect is really really great, except around the edges of less specular portions of the puddles, which have a "sliding" effect when they use lower resolution mipmaps of the realtime reflection. I'd like to find some way to disable this entirely, save some memory and performance, and have highly reflective surfaces act solely as a mask for crisp reflections. I'm theorizing that perhaps I can set the reflection probe to "Custom" and drag in a cubemap that is dynamically updated via script, and have that not utilize any mip-mapping, but I'm not sure if this works properly. I'm trying to get rid of this pixelated blurring effect these mip-maps have... They "shift" a lot, and it's very distracting, even with time-slicing disabled, they just have a poor blur, and it's so close to being perfect. I wish I could alter the levels at which reflection probe mipmaps appear on different smoothness levels, kinda like how you can modify shadow cascade distances. Any ideas?