@Ultimate Sea Dog : Hi! As I still don't have my 4th worker... I don't spend gems to hire pirates (only bought the flag )! But I currently need about 35 minutes to hire all my pirates against about 25 when I was PH4. Still OK for me but I can't imagine how boring it would be for PH8... and how difficult it is to find a island that can be destroyed easily to get BP...
Takes me over 1 hour for a full PH8 attacking crew,so yes my tactics are to hit the low level bases get guild donations and also hit non rumble bases PH that are exposed. That way I can continuous hit and recruit without break. If your matched with PH6/7 then your Ph8 will have a long recruit time and it is difficult not to overkill and keep troups back so I would find it hard to get a good score as a PH8. Although I assume as PH5 you would also find it hard hitting Ph6 bases and your score would also suffer. My best advice is find the easiest bases you can at the start of the rumble, then when options run out suffer the long recruit times.
With 1 million + rumble awards available, I regret that my votes now PH5. To totally fill your Gold and grog every 24 hours at PH4 through rumbles (if you pick the right guild) In my opinion is too much of an advantage/boost.
I don't know if they fixed something since the update... I did 550 BP during the 2 last battles... so it's a way more than 400 BP I used to do... Ok, I had a PH5 and everything upgraded, which is a significant advantage... I will turn PH6 soon, so I will give you a feedback after a couple of battles. EDIT: I remember that the recruitment time is shorter now... but what about BP / fight ?
Once I upped to PH9 I became near useless in Rumbles. Levelling a maxed PH8 yields a whopping 18bp which I can do once an hour.