Holding 110% of ftp for 15 minutes is not bad. The 20 minute ftp test has your ftp as .95 of your 20 minute power, so 105% should be doable.
But I wouldn't start out that way.

IRL, there is nothing like the person that started a minute in front of you fighting to stay there and finally giving up.
Especially if your bike has fenders and dyno lights.