How to Reduce Parameters in CloudFormation Parent Stacks - aws-cloudformation

Question

I'm trying to follow AWS CloudFormation best practices, and set up lots of little stacks that nest under a parent stack. Mostly, this is working fine; however, in an intermediate stack I've now exceeded the max 60 parameter count. This will only get worse when I go the next level up and aggregate these intermediate stacks into a master parent stack.
The CloudFormation documentation says, "To specify more parameters, you can use mappings or lists in order to assign multiple values to a single parameter." In fact, that exact quotation has been given at least twice here in response to the 60 parameter limit question. However, how does one go about doing that? I can see how the mapping capability could work when you're selecting from a bunch of pre-defined sets of values (e.g., select from these AMI IDs, or these subnets), but don't see how it could work when the parameters are strings or numbers or other user-entered data; and I can't see an example at all of how lists do it.
Does anyone have an example or two of how they've used mappings and or lists to consolidate multiple user-entered parameters into a single parameter?
Edit, per a request in comments, I'm adding more details on what my templates look like. Here is the ParameterGroups section of the parent stack in question. It rolls up nested stacks for "mail storage" (which creates EBS volumes), "mail" which launches a primary and backup MX server and configures Postfix, Dovecot, etc..., and "Roundcube" which launches a autoscaling group of web servers running roundcube. All of this sits on top of another nested stack, "infrastructure", which deploys VPC, Subnets, ELB, NAT, RDS, security groups, and phpmyadmin.
AWS::CloudFormation::Interface:
ParameterGroups:
-
Label:
default: Mandatory Parameters
Parameters:
- Vpc
- NumberOfAZs
- AvailabilityZones
- AMIID
- WantRoundCube
-
Label:
default: Recommended Parameters
Parameters:
- AdminUser
- AdminPubKey
-
Label:
default: Mail Storage Parameters
Parameters:
- SpoolSize
- LogSize
- CreateSwap
- SwwapSize
- EncryptedBoolean
- Cmk
- SpoolDelPolicy
- LogDelPolicy
- MasterSpoolSnapshot
- MasterLogSnapshot
- BackupSpoolSnapshot
- BackupLogSnapshot
-
Label:
default: Primary MX EC2 Instance Parameters
Parameters:
- PrimaryServerName
- VirtualUID
- EC2KeyName
- MailInstanceType
- MailSecurityGroup
- StorageStackName
- PrimarySubnet
- InsertTestData
-
Label:
default: Backup MX EC2 Instance Parameters
Parameters:
- BackupServerName
- BackupMailInstanceType
- BackupSubnet
-
Label:
default: Database Parameters
Parameters:
- DatabaseStackName
- MailDBName
- MailDBUser
- MailDBPassword
- MailDBBackup
-
Label:
default: Postfix Primary Parameters
Parameters:
- Origin
- Banner
- RelayHost
- RootMailRecipient
- InetProtocols
- EnableSpfChecks
- EnableOpenDkim
- OpenDkimDomains
-
Label:
default: SSL Parameters
Parameters:
- CertSource
- AccountEmail
- DNSZone
- DNSSleep
- CertFileDir
-
Label:
default: Dovecot Parameters
Parameters:
- MaxUserConnections
-
Label:
default: Amavisd, SpamAssassin, ClamAV
Parameters:
- SAFinalDest
- SAKillLevelDeflt
- SetMyHost
-
Label:
default: Roundcube
Parameters:
- AllowPasswdChange
- AlternativeIAMRole
- AlternativeInitializationScript
- DnsName
- EnableDebug
- EnvironmentVariables
- Hash
- PublicAlbListenerArn
- RoundcubeDBName
- RoundcubeDBUser
- RoundcubeDBPass
- RoundcubeInstanceType
- RoundcubeSecurityGroup
- Skin
-
Label:
default: AWS S3 Configuration
Parameters:
- MirovoyCFAssetsBucket
- MailS3KeyPrefix
- RoundcubeS3KeyPrefix
- SkelFileDir
- Label:
default: Testing Configuration
Parameters:
- UnknownLocalErrorCode
- XandrosPass
- VivitaPass
- ExternalTestEmail
- SSLDebug
- ADLogLevel
- DisableVirusChecks
- DisableSpamChecks
- DisableServices
-
Label:
default: Postfix Optional Parameters
Parameters:
- DelayWarningTime
- MaxQueueLifetime
- MinBackoffTime
- MaxBackoffTime
- HeloTimeout
- RecipientLimit
- SoftErrLimit
- HardErrLimit
- SpfTimeLimit
I'm happy to post more of the template as necessary, but it's obviously already getting quite long :)
Thanks!