[consp]

I'd be more worried about cooling the transceivers properly.

[kohlschuetter]

My optical transceiver gets to around 52 °C (measured via IR camera), well below its design limit, so that's not bad.

If truly concerned, one could use SFP28 to SFP28 cage adapters to have the heat outside the case, and slap on some extra heatsinks there.