Would like to doublecheck that I created a TXT SPF record correctly for multiple IP addresses
Solution 1:
Yes, an SPF record can include CIDR notation:
v=spf1 ip4:173.9.41.64/29 -all
The a and mx mechanisms as used in your previous record result in receiving servers accepting mail from the IP address or addresses of the records of the domain. If those addresses are in the addresses already in the record, then including the mechanisms would be redundant.