You can go IFR, but I think you will have to cancel and enter the VFR arrival. I dont see any gain to retaining the IFR after you start the arrival.
A few years back, I was heading south VFR to Lakeland, as it turned out Lakeland was IFR and alot of people were diverting to Ocala.
When I got to the FBO, there was a guy that said was holding over the Lakeland VOR for a couple hours and had to finally divert for gas.
I'm not sure if he was IFR with a VFR on top or what, but the times I went IFR down there TPA APP would eventually tell you to intercept the VFR arrival.
The one piece of advice I can offer is, do not get pushed beyond your personal limit. Almost every year there has been fatalities because people are stall spinning becuase they think they cant pass an airplane or dont want to go around.
It is true they dont want you passing, but not to the point that your going to spin the airplane becuase you got stuck behind a Katana going 55 kts.
Also, if you are going to camp there, do it over in the general aviation "parking", not the "camping" area. The camping area is alot more dirty and sandy than the parking area, the only draw back is that the showers are a slight hump from the parking, but conditions are much better, and you are alot closer to everything.
I reccomend parking over by the VOR, its quiet and removed enough from all the loud speakers and its a great palce to watch the airshow.