Tails on a DVD (no persistent volume), all asc files and public keys would have to be re-obtained from internet sources for every boot. The downside to this would be finding an internet capable resource to store these >1mb files, and trusting those sources not feeding into PRISM or anything like that.
The other option would be a usb flash drive with TAILS with a persistent space to store all these things (public keys, Private key, electrum wallet, etc.) . One downside would obviously be losing that flash drive, or it becoming corrupt, But I guess which is most important - found by LE.
Please let me know if theres an even better alternative!
I'd recommend USB drive. Assume anything uploaded to be compromised, especially a bad idea with private keys. You can also restore the wallet with a seed, memorize it, and have a paper backup somewhere safe just in case. You can also clone the Tails installation to multiple USB devices if you wish, and hide them around the house. You'd have to be really, really clever with your hiding spots though.