Durable Power of Attorney that is Springing type. Is there a legal way around this?

There are some easier ways to get around this issue.    Since you indicate that she just wants help, but still has good cognitive skills, perhaps the quickest and easiest way is to either (go jointly to her bank, and a) add your name to her bank account, to be held jointly with rights of survivorship, or (b) create a new account just for bills, again to be held jointly.

You can prepare the payments, run them by her just to keep her in the loop.  This is what we did.

As to investments, that's a different story.   If she has IRAs, based on what I've been told by the investment management company, a secondary individual can't be added as a decision maker.    What we did was work out the details, then I conferenced Dad in, then called the holder to request a disbursement.   Conference calling was a real help in this respect.  

The entity confirmed Dad's concurrence by asking personal questions; after that, he stayed on the line while I handled the disbursement issues.

If the investments are stocks, we handled the issue in the same manner, with a conference call.   I honestly don't even recall but my father more than likely had also executed the management entity's very own specific DPOA.

Just a comment on third party entities:  they EACH have their own forms.   After Dad's death, I requested the transfer forms; there are generally 5 - 6, several pages long, from each investment manager.   I rather doubt that they would accept something that's not one of their standardized forms. 

Also, weather depending, we usually went out to lunch, or for a walk or ride, before addressing the financial issues and writing checks.    We were both in a more relaxed mood.   

Since you're apparently not living closely, you might precede a business phone call discussion with relaxing chat, so Mom's relaxed before discussion of monetary issues with you. 

You might also ask the various regular companies to whom she makes payments if they'll send a copy of the bill to you.    Eventually, I changed Dad's receipt options so that I got all the bills.

You bring up the exact reason I never recommend springing POAs. They are too restrictive. Just like you describe, the principal (your mom) might have no disabilities and may be completely competent, but just doesn't want to manage some of the things she used to. She is capable of performing all the ADLs, making her own appts, managing her meds, etc., but no longer wants so manage her finances. Unless you can convince her to change the document, you have no authority to sign for her.

Some people don't completely trust the agent, even a close relative, to act in their best interest so they put these restrictions on them. If you don't trust the agent at the time of signing the document, why would you trust them when you need them most? Just because the document becomes effective on the day it's signed, doesn't mean the agent can act against the principal's wishes. That person still has control over their finances until they choose not to or they are unable to.

Speak to an elder care atty to see if you have any options.

Have her sign the entities forms. They all have something drawn up by their attorney's that allow them to deal with appointed agents. Doesn't need to be your POA.