There are no published guidelines for the max number of tests that can be configured per SRM Host
There a combination of environmental factors that will determine how many tests can be ran.
The ICMP response tests would be considered lightweight.
It is suggested to edit the svcrsp.cf file located within PORT# folder and increase maxthreads from 10 to 50 as a starting point.
Divide out the tests into blocks and then keep adding them until you experience issues in which case you can try to further increase the maxthreads value, or spin off another SRM test host.