I would say no. I have a 20 gallon with 96 watts of PC, and do not think it's enough. I also have a 29g with 225 watts of VHO - I have 3 RBTAs in there due to multiple splits. Believe me, if I thought for a second one would survive in the 20g it would've been moved already...
I don't think you can predict how often a BTA will split. Sometimes they split spontaneously, sometimes due to stress. I've had mine for a year and a half and they first split last July and then again last month. So in my case....once a year. I know of other people with huge BTAs that they've had for years that they WISH they could get to split.....