Multiple SPF DNS Record entries
You can test the existing recursion limits of your SPF records with dmarcian and you can simulate some changes using kitterman's site
I had some folks work with Microsoft to improve their SPF DNS recursion limits. They used to push people right up against the limit.
Update: here is a perl script that you could use to perform the SPF recursion and list all the records that will be applied based on your SPF records.
Without knowing your domain, I could not give you an accurate answer so you could use those tools as a starting point.