One 30 lb and one 20 lb propane tank for versatility?

Interesting. Now I'm thinking about 20s again lol. It's not so much that I want to do exchanges, but I want the option of exchanging if no filllers are available.

That's why I was thinking that using 1 30 and 1 20 would be like the best compromise. Have them refilled and you're only 50 lb vs 60 as the con and the pro being you can use exchanges in a pinch.