I can't speak to the specifics of the CHI workflow, but I can say more generally that there are now relatively inexpensive options in the UAV market that can achieve quite nice results. In particular, the DJI Phantom 4 Professional has a 20mp camera with a 24mm (35mm equivalent) lens that has relatively little complex distortion and produces quite high quality images, at least for a small sensor. This fixed lens can achieve good base-to-distance ratios if proper planning is observed -- it sounds as if you've already learned this with CHI -- and pretty good image accuracy, in my experience. The Professional version of the Phantom can shoot in RAW and has a mechanical shutter so you won't get the rolling-shutter effects commonly seen with GoPros and other lower-quality miniature cameras.
The key is to find good flight-planning software. MapPilot will work pretty well (https://www.dronesmadeeasy.com/), as well an Australia-designed desktop software that connects to the popular Lichti app (http://www.djiflightplanner.com/). There is also the excellent UGCS flight-planning package (https://www.ugcs.com/en/page/photogrammetry-tool-for-land-surveying) but this requires you to use an Android tablet with the UAV. In my experience iOS is generally more reliable with DJI systems.
As I understand it, the CHI workflow strongly encourages the use of cross-strips to increase the overall robustness of the block triangulation. I think UCGS can do this, but with the other apps you'll need to plan a second flight with cross-strips. Fortunately this isn't terribly hard.
One more point I would make is that ground control is really essential for a high-quality project in archaeology, if what you want to do is map features in a site co-ordinate system. The onboard GPS of the UAV will not provide a good solution.
Hope that helps.