i am a certified autobody tech with 35+ years experience.

i bond panels all of the time. every panel i bond also gets welded with squeeze type spot welds just like the factory uses.
the I-Car gold, VW certified bodyshop i work at uses 3M adhesive exclusively. it's says in the instructions to NOT USE IT on floor pans and rear body panels. my guess why is they get to much vibrations and flexing and might break the bond seam. once the adhesive drys it's very hard and rigid.
if you must use it i would recommend the impact resistant panel bond, 07333, over the regular bond adhesive.