Hello,
as for SSB transceiver with less than FT-817 weigh (about 1 kilo itself) you could check:
Elecraft KX2 -->0,37 kg
LNR LD-5 / LD-11 --> 0,54 kg
Xiegu X1M --> 0,65 kg
RS-918SSB --> 0,63 kg (clone of McHF)
FX-9A --> 0,60 kg
There might be more if you search on the web…
Good luck! 73 de Ignacio