I will need to setup a new CAS/MBX server in a DR site.  WAN link can max to about 2MB/s speeds

Main site:  2CAS / 2MBX servers in Load Balanced CAS and MBX1 and MBX2 in DAG of 4 databases

DR Site:  1CAS / 1MBX but I will place this MBX server in Stretched DAG and have passive copies

DR SITE:  I would create the 4 databases on the MBX server, but seeding will take 5 days since I have over 800GB for all 4 databases

If I have backups of my databases in the DR SITE from main site, can I copy them(EDB) and logs and then mount them?  Then add them to main DAG group?  or the only way it can be done is to set up new CAS/MBX servers on same LAN as main servers, let them sync and travel the servers to DR site?

Also, is my WAN link poor in speed for this DR scenario?

Hi Sectorzero,
FYI Exchange2010 SP1 and SP2 is out of support. Please upgrade to SP3.
You can manually seed the database by copying the complete to the exact location in the destination server. Steps below

1.Run the below command on the current server to get the details

Get-MailboxDatabase | fl name, edbFilePath, logFilePrefix, logFolderPath

2. Dismount the database and copy the database folder and logs folder to the server in DR and to thee same directory of server in primary site.
3. Mount the database.
4. Add the databases using the below command

Add-MailboxDatabaseCopy -Identity <DBNAME> -MailboxServer <DRSERVER>  SeedingPostponed

5.Check the content index state using the command below

Get-MailboxDatabaseCopyStatus | fl name, contentindexstate, status

6. Resume/update the database copy. Here is the reference

Resume-MailboxDatabaseCopy DBName\DRServer

7.If status failed you have to update by the below command and make both contentindexstate and status healthy

Update-MailboxDatabaseCopy DBNAME\DRSERVER databaseonly

Update-MailboxDatabaseCopy DBNAME\DRSERVER CatalogOnly