Overall I like the ideas you posted. Rent in advance. Rent from whales. Rent what you need. All great advice. The only thing I might balk at a bit is the rent from Peakmonsters. Peakmonsters is an awesome place to rent cards and for bulk buying I'll go there everytime. However, I think their marketplace and Splinterlands marketplace are the same price, same cards.

Final side note: Sometimes I rent power simply for the same of getting a higher rank at end of season. Right now I'm Gold III but rated Gold I. If I can find cheap power I'll rent it for year end rewards :)