Yes, you are able to travel outside the UK when on a spouse visa.
Although there is no specific requirement for the number of days allowed outside the UK on spouse visa, the UK should be your country of residence.
The only residential requirement stated is when you apply for British Citizenship. it says:-
Residential requirements
To demonstrate the residential requirements for naturalisation, you must have:
- been resident in the UK for at least five years (this is known as the residential qualifying period); and
- been present in the UK five years before the date of your application; and
- not spent more than 450 days outside the UK during the five-year period; and
- not spent more than 90 days outside the UK in the last 12 months of the five-year period; and
- not been in breach of the Immigration Rules at any stage during the five-year period.
If there are genuine reasons, (backed up with evidence) for not living in the UK, then it will be up to the UKBA to decide if they will accept the ILR application.
Another option may be to apply for FLR first, then after apply for ILR?