If you’re reducing the data length, just send the values as a set of bytes. You know from their position what they represent, e.g. third and fourth bytes are Temperature in degrees and tenths of a degree. Also don’t sent timestamps (the receiver can deduce that) and keep your node Identification as just a byte (unless you will have more that 256 of them).
You can actually pack the data into less bytes if you look at the actual range you expect. e.g. temperature that will only be between 20.0 and 50.0 deg C is only 300 possible values which can be encoded in 9 bits (512 values). Have a look at TTN for “encoding and decoding payloads” .
Dave