What math is the best for combining several 32b channels?

I'd like to combine height, two UV gradients and ID  into single 32-bit  gray channel to use it in fx-map node max blending to then split successfully  after.
I tried to put  the height before the comma and  two gradients as passengers after in  digits order  using just floor  and add nodes ?   It works  with one gradient at best , the second comes  pretty degraded due to values precision and  no room for ID at all.   
 

Should I use  some other math . Rather multiplying one to another?    Isn't floating point value should allow to pack lots of info?    Is there any cool advanced way  to do it that could workaround  precision issue?   Sort of bit masks maybe?