There is absolutely NO WAY for the camper to tip over from someone in the cabover bed. PERIOD.
Even the lightest camper weighs close to 1500lbs loaded and ready to camp. BIIIIIG box in back. Teeny-weeny box in front. Where do you think the bulk of that weight is?
There's about 1200lb of camper, appliances, and stuff in the back, and about 300lb of framework, mattress, and bedding in the cabover. Add your 260lbs, and you still have over 2X the weight in the back counterbalancing you.
Front jacks collapsing is something else entirely. In that case the camper did not tip over using the jacks as a fulcrum. The front jacks collapsing changed the fulcrum point to the rear jacks, and we don't live in Looney Tunes Physics world, so the camper clearly would have no choice but to fall over.