For some utterly ridiculous administrative reasons we've got a split domain with one mailbox on Office365 which requires us to add include:outlook.com to our SPF record. The problem with this is that that rule alone requires nine DNS lookups of the maximum of 10.

Seriously, it's horrible. Just look at it:

v=spf1
include:spf-a.outlook.com
include:spf-b.outlook.com
ip4:157.55.9.128/25
include:spfa.bigfish.com
include:spfb.bigfish.com
include:spfc.bigfish.com
include:spf-a.hotmail.com
include:_spf-ssg-b.microsoft.com
include:_spf-ssg-c.microsoft.com
~all

Given that we have our own large-ish mail system we need to have rules for a, mx, include:_spf1.mydomain.com, and include:_spf2.mydomain.com which puts us at 13 DNS lookups which causes PERMERRORs with strict SPF validators, and completely unreliable/unpredictable validation with non-strict/badly implemented validators.

Is it possible to somehow eliminate 3 of those include: rules from the bloated outlook.com record, but still cover the servers used by O365?

Edit:

Commentors have mentioned that we should simply use the shorter spf.protection.outlook.com record. While that is news to me, and it is shorter, it's only one record shorter:

spf.protection.outlook.com
  include:spf-a.outlook.com
  include:spf-b.outlook.com
  include:spf-c.outlook.com
  include:spf.messaging.microsoft.com
    include:spfa.frontbridge.com
    include:spfb.frontbridge.com
    include:spfc.frontbridge.com

Edit²

I suppose we can technically pare this down to:

v=spf1 a mx include:_spf1.mydomain.com include:_spf2.mydomain.com include:spf-a.outlook.com include:spf-b.outlook.com include:spf-c.outlook.com include:spfa.frontbridge.com include:spfb.frontbridge.com include:spfc.frontbridge.com ~all

but the potential issues I see with this are:

1. We need to keep abreast of any changes to the parent spf.protection.outlook.com and spf.messaging.microsoft.com records. If anything is changed or [god forbid] added we would have to manually update ours to reflect that.
2. With our actual domain name the record's length is 260 chars, which would require 2 strings for the TXT record, and I honestly don't trust that all of the DNS clients and SPF resolvers out there will properly accept a TXT record longer than 255 bytes.