As the title suggests, is there any proper way to spawn multiple partners in LCPDFR 1.0 without using a trainer? (As whenever I use a trainer they seem to wander off or stay in the car/van when I decamp.) 

You can go to the station and get a new partner, not sure though. Probably not.

As far as I am aware you can only have 1 partner through the version 1.0 system. I have tried recruiting cops as my partner using the aim+G mechanism but this never seems to work for me unless the cop has just finished arresting someone. Which then causes an aiming manager crash :3

 

I've also tried using the console to do "spawn M_Y_COP" and then tried recruiting them, again this did not work.

 

 

Would it work if you went on duty normally and picked a partner, then once you left the station, you forced duty off, then on again. Would you be able to select another partner by walking back into the station and going to the partner place? Or would using force duty cause your existing partner to go away?

A partner means one. I wish that you could have more officers to accompany you  in the next update/version of LCPDFR IF there is going to be. 

What about spawning them as bodyguards? Or would that just be too messy?

I'm not sure that having multiple partners would be a good idea. I already have enough trouble keeping one partner from being killed because of his stupidity.

 

Cheers.

What about spawning them as bodyguards? Or would that just be too messy?

The system gets confused that way. Your bodyguard/partner will be stuck in an eternal loop of entering/exiting your patrol car.

I guess you could do what stevetrackboyz55 did in some of his videos. He spawned 3 noose as bodyguards and then did a warrant kind of thing with the gta 4 vigilante missions. You can probably have a huge task force if you spawn multiple vehicles.