Yes, I believe that if the aircraft climbed to FL450, under the conditions you outlined, that at an altitude less than 2,000 feet above the service ceiling, the plane would not stall.
The smallest plane I have flown over it’s service ceiling is a Grumman Cougar light twin. The largest plane I have flown over it’s service ceiling is a Cessna Citation. Neither airplane was near a stall. The Citation was at about .6 angle of attack.
I doubt it was ISA +15 or 20 at FL450.
In summary, I’ve done it.
Undoubtedly. Sure it "can" be done. First, not a good idea to announce to the world you busted limitations. Secondly, corporate jets are not Commercial jets. I flew corporate 7 years before moving into commercial airlines. Dont try and compare the two. Third, i am currently and have flown last 9 years in southeast asia. I am pretty sure i know the ISA temps around here. With any kind of fuel and payload, you are not going to even reach your service ceiling.
In fact thinking about it, this is the hottest period of time in the southeast asia. I have not even come close to being able to fly at my service ceiling past two months.
I now have no doubt. In my mind that if in fact it reached 45,000 feet, it stalled immediately.
More importantly, the attitude "i have done it before" will kill you in this industry. As a safety officer, investigating incidents that never make the news, that attitude was the basis of many many incidents.