My 91 TStar also had the wood and fibreglass combination similar to yours. When I redid the carpet I strengthened the middle floor section between the driver and observer seats. I just cut a piece of fibreglass cloth to fit, soaked it in resin and spread it over the backside of the section. Seemed to work OK.
"For every complex problem there is an answer that is clear, simple, and wrong." (Henry Louis Mencken)
2005 X2, Viper Red, MCX, Acme 1285, PPass, rear 750 sacs, KGB, IBS
(previous) 2001 X5, 1991 TriStar 190