GP becomes a useless metric once everyone has a 7* capital ship and is fielding full reinforcements. Similar to squad arena, the differences become much narrower at the upper end of the scale; 20k vs 40k is a major disadvantage, but 380k vs 400k is a negligible disparity. Also, multi-crew ships have way overinflated GP numbers.
As for your difficulties, if you can't kill a 5* Hound's Tooth and aren't going to include what ships you have available to you, I can only offer the following:
https://ih0.redbubble.net/image.507661857.0601/flat,550x550,075,f.jpg
