I would say weaving an oGCD between each GCD is too much, especially if it is random. Not only would you be looking at your bars more often to get the right proc, you will probably find you will tire out much quicker from concentrating for that length of time.

Also, pretty sure you are vastly underestimating how often your quick GCDs would come up, assume a 2.5 second GCD, you get 20 per, need 100, so 5 GCDs, that is every 12.5 seconds you will use standard finish to then go into a high APM phase, to come back down to do it all again 12.5 seconds later. It is too much.