You need to find the right sets of rules for the size of the battle you are playing, playing 1.5k worth of points with kill team rules would be a really slow game.
In previous editions, games over a set point level were considered massive battles, so you had the APOC sets of rules that covered more than just super heavies being n the table. 8th edition has APOC rules in chapter approved, which puts them in open play rule sets and even has missions.
Partninja is correct 8th ed isn't balanced to start with and the problems only get worse the bigger the games are, even in friendly games were players are trying to be fair, the sheer size of the game just means makes it a lot harder to do. GW is currently only really interested on trying to get the system working for tournaments and Forgeworld seems to be dazed and confused at the moment, so open play is the best we have.