i run an old dedicated esky - bit crackd etc. with frozen milk bottles in it - keeps about 2 days if u dont open it every 5mins

whats left goes in to freezer- the bait is normally still semi or fully frozen

 I simply keep the bait on ice or cool and only take out what is needed. 2kg blocked mulies are often alot softer compared to 1kg bagged mulies because of the water content, that may be the issue. As far as squid goes, I dont use store bought, catch your own - they're far better in all aspects.

I've found they stay reasonable if left in cool heavily salted water but still won't refereeze well at the end of the day. 

 I cryvac my squid and try keep them cold all day until I use them 

And for the Mullies I salt all mine I buy a 4kg box at a time and layer them in natural salt like the kind u get for your pool just drain the excess moisture out of the salt box wich is great to keep for freezing with burly blocks even after 2 days on salt they have firmed up enough to use I can't recommend this enough 

When I do trips up north I salt pretty much everything except Ocy and squid herring mullet and salmon fillets are brilliant u don't have to worry about ice at all they can stay preserved in salt for months on end and they firm up and stay on your hook longer 

You can take them out of the salt whenever u like and cryovc them if needed I have done this when camping and had them cryovaced sitting in my car all week , salted fish doesn't smell bad either .

I took 10kg of salted mullies to dirk Hartog last year and they were dynamite caught just about everything 

I would take what bait you have brought home and semi defrost and break it up into say 1HR usage intervals all in a zip lock bag/s water proof and refreeze .
then get a old esky with frozen salt ice in it to keep cold (2 ltr milk bottles with frozen salt water in then smash the shit out of them ) only take out what you need.