Leaving the TH outside is actually even encouraged for pushing if farming in masters is your end goal.
I had my base farming all the way through my time in Masters and had no issues maintaining cups and getting myself a nice league bonus. Loot was saved a good amount of the time as well as a good majority of attacks were snipes, even when I was sitting on near max storages.
If champ or 4K+ cups is your end goal though, it would be best to go for a trophy base as every little defensive win helps.
As a TH8 though this is irrelevant as you will get 100% destroyed regardless up there. Leaving the TH out is just fine as you aren't going to be winning many defenses.
And I think you meant Masters for the 1k gems. Champ is going to be a much longer road as a TH8, and I believe that is for 2K gems.






