Didn't read all the posts...
Years ago, it was difficult to do all my banking via WiFi but it was possible. Naturally, as soon as 'automatic' payments became available, I jumped right on that. Since I'm a full timer, I don't have a lot of recurrent bills anyway but the autopay means I don't have to worry at all.
Unless you're going to be boondocking (keep in mind that some areas in the forests can't get cell phone either), then just do your banking online using RV parks WiFi.
As far as security goes, if you have a strong main password on your computer or tablet, and different passwords on your accounts, bad guys won't bother with you. And if you camp in smaller towns, the odds are even better you won't be hacked.
Ten years ago it was difficult to find RV parks that had good WiFi, now it's unusual to find parks that don't (at least for banking and normal surfing).
And the best part is that it doesn't cost $60/month extra.