Your idea would be great but you have to remember the character that you are playing story. Any human character only has a very small percent of saiyan dna within them. That's why shenron is needed just to unlock the supersiayan transformation. with the little genetics humans have with the saiyans its impossible for a human in this dbo timeline to obtain the super saiayan 2 transformation and beyond
Oh thank God we have the concept of Super Dragon Balls, "unlimited rules'' 