[DrPraetorious]

How's this for a proposal:

Sloth -3 =
-45% resources,
unspent resources do not accumulate towards province defense, province defense has a 15% chance of degrading 1 pt each turn,
building costs increased by 30%,
forts take an additional turn to construct,

Sloth -2 =
-30% resources,
unspent resources do not accumulate towards province defense, province defense has a 10% chance of degrading 1 pt each turn,
building costs increased by 20%,
forts take an extra turn to construct.

Sloth -1 =
-15% resources,
unspent resources do not accumulate towards province defense, province defense has a 5% chance of degrading 1 pt each turn,
building costs increased by 10%.

Prod +1 =
+15% resources,
10% of unspent available resources accumulate towards province defense,
building costs reduced by 10%.

Prod +2 =
+30% resources,
20% of unspent available resources accumulate towards province defense,
building costs reduced by 20%,
fort construction time reduced by 1 turn.

Prod +3 =
+45% resources,
30% of unspent available resources accumulate towards province defense,
building costs reduced by 30%,
fort construction time reduced by 1 turn.

Available resources exclude hidden resources and include resources brought into the province by forts.