I can't see a problem with Geoff joining in for the last round. Monza is certainly one of the best known circuits, so he won't be on unknown ground.
I guess the only thing to be aware of is avoiding contact at Curve Grande on Lap 1. The most common place for over ambitious speed on cold tyres and with a crowded track. In fact there are those amongst us who deliberately hold back here and bank on gaining two or three places as the "fools rush in where angels fear to tread"!!!!
Seriously though, I suspect that the speed of the likes of Hristo and Lorenzo when they begin to close from behind will be the thing to watch out for.
Either hold your line and let them go around you, jinking out of the way at the last moment is a sure recipe for disaster!! or if you see them coming especially at Monza on the straights, just ease back gently on the loud pedal, hold your line and let them pass. If it looks like they will catch you in the middle of Parabolica, don't panic and try to go faster than you can hold on a true line. It is better from their point of view if your trajectory is constant and you are not fighting armfulls of opposite lock or a wildly fishtailing monster.
I'm sure Hristo will have some words to say on this one
BTW all the above can be ignored if it looks like Hristo will lap me with only a few laps to go. In that case I will invoke the moderators blind eye and you can weave and block him as much as you like.
Unfortunately, I doubt it will slow him or Lorenzo more than 2 nano seconds