Good News!!
I was thinking the grommet/boot would stretch quite a bit, but I haven't done that style so I can't say if it could have stretched that much. I know on my 96 its not easy either, but the boot definitely had to be out of hole in the hull, or the connectors would never pass. On the 96, its a large group of connectors rather than one large one. I'm a little worried that the glue might fail on you, but that shouldn't be too bad too replace if you need to.
The gauge itself should be pretty secure just being pressed into the rubber grommet in the hood. I used a little soap & water when I pushed mine in place, they were still very snug, If I remember correctly the grommet had to be fitted to the hood, then the gauge pressed in.