How can I use Trainer FTP to inform a MTB Pacing Strategy?

Ok I am fairly new to indoor training, and really new to racing. I have a mtb gravel hill climb coming up and am curious if I can use my trainer ftp to estimate how much power I should be putting out on the hill climb with high volume, knobby, mtb tires. Essentially how can I use my indoor ftp to inform my pacing?

I’m not looking for anything super scientific here, just a ballpark percentage of ftp that takes into account race length and tire rolling resistance.

If I had to guess the race will take me about 1.5 to 2 hours long on a gravel road and I’ll be on wtb riddler tires.

Any guesses? -10% for knobby tires, -5% for 2 hours, as hard as I can till I blow up and puke? Thank you for all your help!

Have you looked into Best Bike Split? Is this a straight uphill gravel road climb and nothing else or is this an XCO or XCM race?

I looked at best bike split briefly and it didnt seem like it looked at mtb tire rolling or gravel. It is just a local gravel road climb as part of a race series here. Seems like an uncommon race type