Dry Rot Repair - 1989 Supra Comp

I discovered a soft spot in the floor on the observer side of my boat. Managed to pull back the carpet without destroying it. Underneath I discovered a thin 4 inch crack which most likely caused the dry rot. I cut out a section of the floor to assess the damage. The foam doesn't have any mildew. The main stringers feel solid. However, there is a cross support beam that is soft.

I am not sure what the best way to proceed and could use some advice.

Should I remove the front seat and replace the support beam? If so, how do I get it out?
Or should I inject the support with Clear Penetrating Epoxy Sealer?

Any advice or tips on repairing dry rot would be appreciated.

Here is a photo of the repair project. (May 10, 2005).

[Albert Girardot]

We'll like many older Supras this eventually comes. You need to pull up the carpet and inspect everywhere. If you have any soft members you need to replace them. My first Supra I to noticed a soft spot similar to yours. The following winter I tore up the entire floor from the dash to the rear. Replaced several support members, the foam and the floor. Big job but it held up perfectly. However, I have the advantage of boat building experience.
Adding sealer to your soft beam is a waste of time. This stage in the season I would do a temporary repair to the floor, glue the carpet down enjoy this summer and research and plan for a winter project. Many on-line sites you can purchase composite members and fiberglass panels. If you search this bb you can find real shit job repairs others have done using pressure treated wood, poor workmanship and no clue on what they were doing.
Good luck.

In other postings, this is what I learned about the spotters seat and removing it:

You will see that the spotters seat is indeed molded to the top, so the whole top would have to be raised to get under it. (fixb52s)

I used a small hydraulic jack with wood blocks to lift the top of the boat at the windshield area, this raises the observers seat base, which is molded to the top, just enough to allow the use of a long wood chisel that I made from a piece of 1/8 in.x 2in. wide steel and 3ft.long to split the floor from the stringers. At the back of the boat I used wedges to lift the bottom of the seats(molded to the top of boat) and my trusty chisel/hammer combo to remove the floor from bow to stern. (f9captnemo)