I have a question tho: if you choose "Max" as the amount and export the signed tx, what happens if between the day you export it and the day you broadcast it, the input receives more BTC (say you now have 0.77 instead of 0.7514)? Inside the signed exported tx, is the value specified as "max" (0.77) or as the value your input had at the time of signing it (0.7514)?
You'd have to keep updating what you're doing, but I think this should be treated as a method on your portfolio such that you'd pick amounts to increment on before making a transaction.
For example, a while ago I had a multisig with a few different devices and I'd only send funds from my hot wallet to them once it exceeded a threshold of 0.25
BTC. I normally have SOME online assets stored without protection anyway (a few mbtc just in case I need them for something) so these would be much easier to recover - some funds might be lost overall but I think this allows for a large amount of someone's funds to be passed along - if not all.