I started out using your method and it worked pretty well, but I disliked the randomness. This might have been because I got unlucky and didn't get the craft runestone until fairly late into my grind (it was under the toad runestone that seemed useless), many of my attempts, I wouldn't be able to get any of the secondary rewards (kills, followers, etc) so I messed with some options and here's what I came up with:
1) Enable Talisman Bloodbath and Runestones in house rules. Enable both the City Expansion and Sacred Pool Expansion.
2) Use the Runestones of Brawn (starting strength), Thought (starting craft) and Wealth (starting gold). Until I found the Thought stone, I used Power (trade in less trophies for strength)
3) Player 1 selects the Assassin. The Assassin begins in the top left square (the City) adjacent to the City Expansion area. Player 2 selects the Cleric who will start in the lower left corner on the Chapel square, two away from the Sentinel.
4) The Assassin was selected for two reasons. The first is that they can skip fights via the "Assassinate" ability if their strength is equal or higher than the enemy. Die rolling back and forth takes a lot of time, and being able to just hit "Assassinate -> Auto-Win" saves time. Even at default values, the Assassin will always beat the Cleric as well, which is nice.
The other reason is the expanded City area. It basically consists of a straight path (which can have random encounters) with a shop adjacent to almost every square.
5) The Cleric was selected instead of the Prophetess because she starts with only 3 life. Strength is also low enough that the Assassin can always beat her (if attacking) and the Sentinel can auto-win, skipping the fight animations.
6) My plan was to send the Assassin through the linear City (optimally) to the Menagerie square. The Menagerie square lets you buy a pet (follower award) for 2 gold (gold spent award). In going through the city, I would usually hit two other encounters. If I got a follower in one of those, I would just swing into whatever shop was nearby. Creatures tend to be physically weak and the Assassin could kill almost all of them without entering combat with the strength runestone maxed out.
If I rolled a 6 on the first turn, I would instead go attack the Cleric directly for the PVP award credit.
7) The cleric would always directly attack the Sentinel, auto-lose then select to take damage.
With this setup I was consistently getting XP for followers, gold spent, highest strength, and highest craft (eventually). Sometimes enemies killed / trophies used, etc too. I timed a few of the games and was getting times like 1:03 or 48 seconds. I believe my fastest was something like 18 seconds with a specific encounter (Assassin encounter lets you pay gold for damage. 3 gold = 3 life = Instant kill on the Cleric).
Nothing wrong with your method. Just thought I'd add my version,