Advertising a /28 as a /29 over BGP. Possible?

Bear with me :)

I'm setting up VRRP on two routers. The customer has a public /29 and instead of eating away at 3 of these IP addresses for VRRP, instead I want to increase the router interfaces with VRRP on to a /28 but I need to advertise it out as a /29 as this is what the customer owns.

Example : Customer owns 8.8.8.8/29

VRRP Router1 : 8.8.8.1/28
VRRP Router2 : 8.8.8.2/28
Standby IP : 8.8.8.9 (falls within their actual prefix)

Customer can then use between 8.8.8.10 to 8.8.8.14 on the inside of this as a /29.

A static route to null 0 for the 8.8.8.8/29 and then re-advertising that won't work as it would get preference over the connected interface due to it being a more specific prefix.

Is there anyway this is possible? I know BGP won't advertise something it doesn't see in it's routing table. It will see the /28 of course but I can't have that advertised as a /28.

The alternative is using a completely different (private) range for the VRRP but it get's a bit messy for the customer this way.

Thanks