As for this proposal, it is permissible under Section 4 of the 25th Amendment. The Cabinet may be replaced with "such other body as Congress may by law provide". However, this proposal is nakedly political. The sponsors of this bill expect this commission to immediately declare the President disabled. This would then put pressure on VP Pence to agree.
Even if amazingly they succeeded is having Pence become Acting President, Trump could then declare himself fit for command. Pence and the commission would then have to challenge this declaration for Pence to remain Acting President. Congress would then have to decide the issue (see second paragraph of Section 4 of the 25th Amendment for details). No way would two-thirds of each House of Congress side with Pence and the commission. This would result in Trump regaining the Presidential powers.
Note again: at no time would any of this result in Trump being removed from office. The supporters of this bill are not only desperate to remove President Trump from office, they are too stupid to know which part of the Constitution deals with such removal.
Realistically, it has zero chance of passing the House.
They’re livid at Trump for not being a roadkill Republican and they don’t know how to deal with him.
Trump is not their real problem and they need to figure out why they keep losing elections.
This is not a winning party, however they tell themselves they’ll stage a comeback in 2018.
That’ll happen as soon as they behave like rational adults. Good luck with it.