This is not the way to go with GP. Keep only one channel active for the whole keyboard controller and do your splits using multiple PX-5Q MIDI in blocks. Each MIDI in block can be connected to the plugin it should control (no need to use different MIDI channels) and has its own split (min/max notes) and transpose (especially usefull here to adapt the octaves of the plugin to the position of the splits on your keyboard controller.
Using splits directly on your keyboard controller, could even be dangerous and lead to stuck notes. E.g. if you play a note (note on message) and change the settings of your keyboard controller such that when you release the note (note off message), the released note has a different channel/split/transpose.
Additionally, using only basic capacities of your keyboard controller will make your rig independent of this particular controller. You should also have a look to the Rig Manager. Using the Rig Manager if your need to replace your controller because he broke or whatever, you have a different controller for home/stage/rehearsal, then you will be able to seamlessly replace it by almost any other controller available.
Regarding multiple rackspaces active at the same time, it is not the way to use GP. You can have one active local rackspace and the global rackspace at the same time. This means that everything you need has to be in one rackspace. But you can change from one rackspace to another instantly without audio glitch. It is important you carefully read the manual and try to understand the concepts in GP for you to get the best out of it.
Have a fun with GP 