I noticed issues in the Last Heard Peeking (LHR) functionality:
The message is sent in local time - but it should be sent in UTC!
The message is too verbose - abbreviate the message, to reduce airtime. A. Do not report seconds. HH:MM is enough. B. Delete BEACON, it is redundant. If you can report also broadcasts - that would be best, so then it is not redundant, but should be abbreviated (e.g. BCN vs BRCST). But maybe it doesn't matter how it was heard? Just delete it! C. Remove "dB". It doesn't appear under SNR, why send unneeded data here? D. After all this, remove ">" and "/" and just use white space to separate the columns.
E. Ideally, pretty print it, so the columns are aligned and human readable. F. If you do this, you could pretty-print it in the client, to save airtime. G. Compress the message before transmitting over the air: e.g., most of the time the band will be "20m" so why it is redundant to send the same text - just replace it with a short unique symbol for each band!
Example
timestamp will be fixed to UTC.
Rest of your suggestion is rejected.
(FYI - compression is enabled by default for all VarAC traffic)