Hi Marc,
Initially it’s pretty typical for people to resist the b9/#11 combination with dominant chords – it does sound a little dissonant. But in context it adds to the harmonic interest.
A couple things: If you’re playing an acoustic piano make sure it’s in tune. Stick with the voicings as written – you’ll have lots of opportunities to make your own choices later and you need to become accustomed to this way of hearing dominants.
The voicing you suggest: 1,3,5,M is a basic major triad (with the melody – a 6th), so while the b7 is in your right hand the overall chord doesn’t sound much like a dominant.