I have a cousin who doesn't drive who lives in Tampa. I picked him up in Tampa one time, had him spend the night at our condo and most of the next day and had him take the train back with a friend who would pick him up. I Just wanted to say that the train is not always on time. When we waited with him there it was almost an hour late. You need to figure how far the train is from where you want to be in Tampa too. That might involve taking a local uber anyway. Maybe even one to the train and then from the train to your venue. Might as well in that case rent a car or get an uber IMHO for more convenience.
I have also on another trip picked him up in Tampa, had him spend three nights with us in our condo and got him an uber to go back to Tampa. That was way easier but a bit nerve wracking as uber drivers did not want to go all the way to Tampa and the first two declined to pick up the trip even if it is against policy. My cousin was quite nervous about that, but I told him not to worry and if it came to it I would drive him back. I just really didn't want to do all that driving though having already done that a few days earlier. The third uber driver happily took us, and I gave my cousin $40 to give the driver as a tip, knowing it was so far out of the way and wanting to make it worth his while. The uber ride itself was $70 dollars back then from our condo to his apartment. The guy was super nice, and my cousin felt very safe.
If I were to do this trip to Tampa in your shoes, I personally would rent a car or take an uber each way. With the uber if you choose that, make sure you are not a person who will get flustered if you have to try uber more than one time to get a driver, and I would suggest tipping whoever takes you generously.
I also have to say that although I have done it many times, I really HATE the drive from Orlando to Tampa and back. There are lots of crazy people on this route who do a lot of weaving in and out of traffic. In reality though it seems there are more crazy drives on the road everywhere. One time too (bad timing on my part I just think) I left on a Friday around 5 p.m. to get back to Orlando and it took me three hours (without traffic issues would have been an hour and 20 minutes) -- tons of people from Tampa going to Orlando for the weekend. Please note that I don't like drivng in Orlando these days either -- but it could be I'm getting older -- 63 now, it could be that I don't do a lot of heavy traffic driving -- since the pandemic I work from home full time - pre pandemic I had an 18 mile each way every work day commute, and it may be too that there are more crazy people on the road than there used to be). It's probably a factor of all three, but really and truly I used to think driving around Orlando and back and forth to Tampa was easy peasy, but that has changed for me in the last five years.
And several times I took the SeaWorld bus to Busch Gardens for the day and back (free with a Busch Garden ticket with pickup from the SeaWorld parking lot (met my cousin for the day there -- this is back when he could do local driving to Busch Gardens and meet me there -- now he doesn't drive at all). This usually worked really well for me, but one time coming back we ran into a bad accident and the trip took an hour longer than expected. Just saying accidents on this route happen pretty often too, so bring your patience for possible delays.