It seems to be possible to download all data (including answers etc.) for Lab-Caches as an .gpx-file, I just had the experience of someone, who didn't do the Lab-Cache, but got all answers, thus the coordinates for the Bonus-Cache and was the FTF at the bonus. Luckily I knew him, and got it sorted, and now the real FTF will now get the credits for that. I have not deleted his log, as he was at the container , but I think of this bonus caches as something like a challenge: You're only allowed to log, if you have done the lab. If you get the coordinates in any other manner, you're just a cheater.
I only cache with my mobile, so I'm not accustomed to Garmin and such, how could it be prevented, that anyone could do the Lab-Cache without crossing the fences? As this should clearly be prevented, or those Lab-Caches are just some tourist information tool, but have absolutely no connection to geocaching.