I think a confusing part for some people (myself included) is that the ramp test is used to estimate FTP. But it doesn’t sound like you care about FTP, you care about the last minute of the ramp test (i.e max aerobic power.) You’ve also indicated you think you are anaerobically inclined, which could mean you are more prone to over performing on the ramp test. Am I correct in thinking that you don’t really care about your FTP directly, you want to raise your MAP to 400w?
I think the confusion is that, if getting your MAP to 400w is the goal, just make that your goal. If you want to reach 300w FTP estimate on the ramp test (which would require approx 400w MAP) but don’t actually care that the number is a semi-accurate estimate of your FTP, it causes confusion. It sounds like you are trying to ‘game’ the ramp test. Which is fine, but for training threshold and below its better to have a semi-accurate FTP estimate.
As I think someone else mentioned, I think it would be worthwhile to do a longer test like the 20min test to get your FTP set. Then use the MAP from a ramp test to set your VO2max interval intensity. That way you are not doing all your SS/threshold work at too high of an intensity but also do VO2max work at a high enough intensity.
All that said, I have some unstated number goals for myself, but I don’t know if they are possible given my time training and riding, age, and genetic factors. I think it is better to lay out a training plan to follow that gives me a path to get to that ‘goal’ but make the actual goals I try to tick off be process focused. There are factors beyond your control that could prevent you from getting to a 400w MAP, so focus on the things under your control that give you the best shot of getting there.