Yes, unfortunately, there is no way to get to the flexplate bolts that bolt to the crankshaft, without removing the transmission....
5 hours is rather conservative...doing this at home is almost next to impossible....in a shop, it would be high on a lift, support the engine from above, remove the cradle, separate the tranny from the engine and lower it out from under the car....
You would have to get the front end of that car up pretty high, to drop the tranny enough.....
Your other option, is remove the hood and cherry pick the engine/tranny as one unit....then separate the engine from the tranny...it's way more work, but it's an option....
Attempting to do this on the ground at home, will be a nightmare....
A lift is your friend......or find a friend with a lift.....