Trailer a K12...? On/Off Centerstand?
Plenty of personal experience trailering my '03 K1200rs.
Re: Front area, I use soft ties and make a loop around the top of the fork (left and right) just above the front fender and angle the strap forward and connect to a ratchet tie down and compress the suspension about 50%. In back I use soft ties to a rear frame member, on the left, right near the hand grab for putting the bike on the centerstand. I would never tie to the bag supports, but that's just me.
Re: on the centerstand....no knowledge, only an opinion. If your trailer is a singe axle, while moving down the road, the entire trailer and bike will bounce over pot holes, railroad tracks, stepladders in the middle of the road, etc. So now, all the bumps you are hitting are transferring the impact to anything connected to the frame....electronics, engine, etc. Don't use the centerstand and let your bike's suspension do it's job.