I had my caravan storage inspected today by a nice older lady who is covering this area and everything passed. Hopefully others can find this information useful.
I put in one of these
Attachment 208372
Used coach bolts M8 due to the rounded head and square first part of the shank
Attachment 208371
Through the chassis with shear nuts, permanent loctite and hammered the ends of the bolts over
Attachment 208373
Ammo and bolt to go into a separate lockable metal box and stored not in the caravan unless occupied.