We have a thread discussing 2 ship rebel lists, where it seems that 2 YTs might be interesting to run (and its possible to run 3, though I haven't seen much discussion there).  Given that A wings run a low 17 points, its pretty easy to run 5 ships in a rebel list.  I think my first take on wave 2 ships might actually be a 5 ship rebel list, something like this:

Rookie X-Wing
Rookie X-Wing
Gold Squadron w/ Ion Cannon & R2
Prototype A-Wing
Prototype A-Wing

The A's would probably lead the charge, followed up by the 2 X Wings and the Y-Wing.  Of course thats all low pilot skill, so how about at least one high skill pilot:

Tycho w/ Push the Limits & Stealth Device
4x Prototype A wings

That list is the Tycho show, with the other A-s running interference.  Still that doesn't have any synergy - what if we throw garvin in there?

Garvin w/ R2
Rookie w/ R2
3x Prototype A-Wing

Anything interesting 5 ship wise that others are looking at?

You're first list is exactly the same as the list that I posted elsewhere (I'm not meaning to imply that you stole it).  

To quote myself "this build is designed to make use of the tankiness of the Y-wing, ensuring it has an ion canon to help the fighters, leaving one point available. You could alternatively leave the 1 point out and go for initiative, or in this case - I decided on the r2 unit to help let that y-wing maneuver a bit easier."

There was some talk about the r5 being better than the r2 on a y-wing, and the downfalls of low skill level pilots. I also posited that there may be an advantage in using missiles with a-wings over a fifth ship.

Also, there were other 5 ship list sugestions by other people which i liked:

3 Rookie X wings, 2 prototype A-wings

1 Green Squadron (squad leader) 2 prototypes, 2 rookie pilots with droids.

Also, it's possible to do an outer rim smuggler, gold squad, rookie pilot, and 2 prototype pilots, though no ion canon for the y wing - could drop the y-wing out for another a-wing…

It's hard to fly the five ship rebels because points spent on upgrades are spent on a ship.