I would resent having to use LEL as a means to boost other events. If other AUK events are struggling, those organisers should perhaps ask why that is the case at a time when you can't move for successful cycling events.
Any boost would just be a side effect to qualification requirements. (and bear in mind that AUK owes its existence to riders needing to qualify for PBP!
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We could look at the PBP pre-qualification model (used in 2011 & 2015). This seemed to work really well. It only involves 1 ride, so that should assuage your reluctance to bully people, and require much less admin than the whole SR thing.
Another option is to allow non-AUK rides - thus reducing the bullying factor further - and/or even big rides outside the standard BRM formula (LEL's discretion). Again, if this is done in the season before, the manic rush of admin will be mitigated.