SBBV and SBSN are the best options, specially flying at night. You can actually use SBMN to actually alternate but not file it, consider it as a back-up, its very close to SBEG. If you speak portuguese Itacoatiara (I think SBIC) is close to Manaus, but has no fuel and daytime only. And there is also SWPI halfway to SBSN, its a municipal airport, call there upfront to make sure they will keep someone there, but again I guess, still no fuel. SBTF is maybe some minutres closer then SBBV, has a nice RWY, can operate at night on request, fuel (Shell/BR) but might could be a hard time without Portuguese again.
In SBEG you could consider waiting for weather improvements in case of TS Floodrain, or traffic, as usually those problems dont usully last more then 30 mins, The only thing really though can be fog forming at night and can last untill 10:00 LT! ILS not a must, most of the time ceiling is abv 1000ft AGL.
Have fun!