Thanks for the concern. I was only using those numbers as an example -- my actual situation is not nearly so "dire"
. And it's no big deal really -- in doing lots of quests early I levelled up without caring too much about A/D strategy. Now, as you suggested, I get do attacked by rivals pretty regularly but I lose almost nothing because all of my cash is either in the process of being spent, or in the vault. Since it costs noting to rebuild unit buildings and I only lose a little from money buildings... meh. So my plan now is to turtle for a while, building up resources without levelling up.
Interesting thought about the end game -- eventually, because of the cap on allies, will everyone will end up bunched around the same A/D except for those who have paid actual cash for the better units?