Disclaimer: This solution may annoy other plays as it involves idling.
The way I idled some of this achievement was to go into a server, at team select pick the mason order then just stay on the choose a class screen and the mason order playtime will increase, whenever a new round starts you will need to pick the mason order again and continue to sit on the choose class screen. You may of course get kicked from the match if the other players notice you are just idling, but since you are not spawned it is less likely.