do you even understand what an RCD does? if you do, you wouldnt be asking something like 'can i change an RCBO for an MCB without comprimise', because there is a big comprimise, there is now no RCD part. and if its tripping all the time, then there is a fault, removing any safety devices wont remove the fault, only hide it. at least until someone gets killed or the place burns down. good luck defending that one.At this is a temporey site could i get away changing the shower breakers to mcb with out comprise as this is what we had to do with most of the main distubution board at the end of the rows take out rcd main switch and fit normal main switch ???
maybe you should get someone competent to have a look at it and find the fault, since you cant.