The incremental routine is rather new because I invented it a while back and have been testing it on myself. For me, it is the best routine I have ever used.
I think you should try it. For you, you would start your first 5 minutes at 2.5”hg, the next 5 minutes at 4”hg and then the next 5 minutes at 5”hg.
If that goes well, after a while try 4 increments starting as above and the final 5 minutes at 6”hg. That will be 20 minutes total. If that goes well, then you can try extending the final 6”hg setting up to 10 minutes and then eventually 15 minutes for a 30 minute continuous session.
Try an every other day PE schedule so you get good recovery between each session.
If you try this and it works, be sure to leave feedback on your results.