Just some personal opinions,
In that ratio of herb-dmt, that could end up being on the lighter side as far as the experience goes, unless you were just to load more, though by loading more that would in effect be alottt to take in [lots of herb there to smoke, along with the infused dmt, + the harmalas].
2:1 ratio, and other potential ratios, I mean those are totally fine and all, but I prefer 1:1 of dmt:herb. Many other members here do this ratio, and if you're looking to go deep [not that that has to be the goal], then a 1:1 ratio is fairly failproof in terms of the amount needed to breakthrough. Much less needed to smoke with the 1:1. I'd imagine that loading a joint of the ratio you listed above to be a fairly weak experience, unless this is what you were after, then in that case all is good.
Though in the end it's completely your call, just offering my opinion.
The amount of caapi freebase you were planning to use seems legit, mediumish amount of harmalas relative to everything else you listed. I'll usually use 250-300mg caapi freebase per 1g dmt, the harmalas don't seem to impart much if anything into/throughout the dmt experience, aside from how the harmalas slow the experience down a couple steps ime. Several other members here use this harmala
mt ratio in their changa.
With that said some seek the more harmala heavy changa blends, though I'd imagine there could be real intense somatic effects from the high ratio of harmalas to dmt, probably hitting close to being ayahuasca-similar. Can't really comment on the harmala heavy blends though or it's similarity to ayahuasca, though I have taken chacruna/caapi, and idk .. I can't imagine it being like or even similar to a brew, but I could be wrong.
Anywho, hope it all works out for you. <3
* Also, for changa or enhanced leaf there is little better of a device than a smaller glass bong, or even potentially better - a smaller glass bubbler, and with either of those load ice cold water. Very effective delivery methods imo