My BPDh has issues with overspending and public generosity, but he does more of the controlling, hiding, not wanting to invest.
We've been married 24 years, so my system has been a long time in the making, but it works well for us. Of all our issues, this one has improved the most.
The most important thing seems to be having consistent rules, that don't change. The hardest part is setting up those rules. They have to be rules that he is a part of making, and deciding on, so that can take some time. But once they're in place, it seems to get easier and easier, because they become more automatic over time.
For the control issues, we each have a budget, that only changes if more money comes in, or goes out, on a regular basis. We split those changes 50 - 50. Then, if we need to spend outside of our budget, we have to make the decision together.
Separate budgets are essential. That way, he doesn't feel like he needs to control my spending, and I don't worry about him spending in ways that I don't agree with. It also enabled me to use auto pay and online banking for my accounts and my bills. Then, after I used them for a while, he had less fear of them.
Eventually, he was ok with me setting up all of our bank accounts online. We both have access to all accounts, but I manage them, so that it's organized and well looked after. I can see all activity right away, but he can too, so he doesn't feel controlled. He hates change, and loves for me to do things for him, so I've actually had to push him to learn the passwords, and take equal ownership of the new system. I think that's important though, so that he doesn't build resentment.
I use auto bill pay, through our online bank accounts, for any bills that don't already have an auto pay option. I've slowly been getting everything else changed over to auto pay. That way, bills automatically get paid first, and it's easier to see exactly what's left over. He's never been one to over charge on credit cards. I think I would separate things more, if his behavior was affecting my credit score.
For investments, I find that what works best, is to do a really good job of laying out a presentation to him, that's super clear. For example, I manage our rental investments. So, on a recent renovation, I showed him a budget of every dollar, and a few possible outcomes of how that money should increase our income.
I've even put together photos in photoshop, of what the end product of a renovation would look like. The better he can see the situation clearly, the better he can regulate his feelings.
He has a really hard time seeing the long term, because he's so stuck in his fear of losing something. I realize I might always have to be the one to be the guardian of the big picture, but I also want to leave him room to take on more responsibility.
I hope this helps