I think the way I play this game by now I'm never getting matched with anyone. :(
My first Invader got to me in Oolacile Township at aroubd lvl 80
I think I might even prefer the stupid soul memory system to this equipment based one.
As a summon I usually like to hang back and let my summoner explore, and only go in in emergencies and bosses.
For that I always had a low lvl character at the end game ready.
In my first run in this game though I never saw any summon signs or got invaded, nor got summoned until almost the very end.
Twink invasions in the burg suck, but come on, that's at max a 15 minute diversion! This system makes sure your efforts to sequence break go to waste completely, and the freedom to seek this out is what makes DS1 my favorite game ever.
I'm a little disappointed now that everyone HAS to do a vanilla playthrough to even get a chance to be matched at all. :/