As soon as you take a paper wallet key to an online machine, you can consider it compromised, this is why it is recommended to use a paper wallet only once and transfer the rest of the balance to the next unused one, if you still persist on using just one cold wallet then you need to make transactions online and sign them offline, which would require you to run a watch only wallet and that requires a master public key.
Can we consider the paper wallet as compromised even after taking all the precautions mentioned in my description.(1) Using a dedicated machine with no writable media
(2) Using TAILS - clean Linux OS with no malware
(3) Not using the persistance feature of TAILS
(4) No connection to any LAN
The private key will be written to the RAM, since the home drive of the user will exist in RAM only, by using a password we ensure that what gets written to RAM is the encrypted pasword.
Maybe/maybe not, but the term cold wallet refers to that it must stay off-line which is why it is recommended to not use a paper wallet twice but if you're confident that its safe you can go ahead and re-use it but I wouldn't suggest this to others. It isn't like it costs anything to make paper wallets, why go with all the above steps which are tiresome, when you can simply print any number of paper wallet and use them one after the another, which is much easier to do. Or as I mentioned before running a cold wallet with Electrum is even easier.