It is however very odd that the Diffserv mode has any effect on this at all.  It could be explained if a lot of the traffic is marked CS1, since the Bulk tin has looser AQM parameters.  That suggests that selecting 'satellite' might help similarly.

Something worth trying would be to alter the failsafe shaper's rate of advance.  Currently it has a one-quarter rate, which might be too restrictive.  Tests at one-half and three-quarters might therefore be interesting.  Otherwise, I don't think trying to modify the way ingress mode works will do the right things.