I haven't tried this strategy yet, but an idea for getting the 90,000G win fast is to play a Blue Kelpie Book on Stairway to the Gods. Focus on getting a beefed up Kelpie onto the land directly in front of the Temple and the fort closest to the castle. Once the Kelpie is in place go back and forth to the temple buying as many blue symbols of your current area as you can. Include Permission and Aurora in your book. That way you can cast permission when you've spent all of your money on symbols and focus on getting back to the temple to buy more. Don't use Aurora until you have a TON of symbols - like thousands. You want to be buying them cheap. The reason this should work is that the AI will often avoid a Kelpie if there is no way to defeat it, so they will be left roaming the map unable to do anything but discard. Once you have purchased hundreds of cheap blue symbols, start laying down more of your blue creatures in the central zone, convert them to blue territories, and level them. Don't buy any more symbols at the temple, however cast Aurora as soon as you get it.
Honestly, using symbols effectively on Stairway to the Gods is often the key to victory. The reason that this strategy should be effective to make the 90,000TG without spending 9 hours is the use of Kelpie on a key land to shut down the AI which allows you to go all Gordon Gecko, buying investments for 20-30 rounds and then skyrocketing the value in the next 20-30 rounds.
Use Kelpie, Living Mirror, Reflection, Fat Body, other Blue creatures, a few items, Aurora and Money Spells and you should be good to go.
I'll try this tonight and let you guys know how long it takes me to get 90,000TG.