Turn a dumb sensor into I2C
If each sensor has a small micro controller you can have them addressable via UART.
All sitting in RX mode until they get their addressed command, and then they respond.
Pretty standard method.
To be clear, the sensors would all be &quot;daisy chained&quot; together in parallel, power, ground RX and TX.
UPDATE:
The max distance for both I2C and RS232 (or any transmission really) depends on the cable capacitance.  The maximum cable length is 50 feet, or the cable length equal to a capacitance of 2500 pF.  Using CAT5 cable you get this:
RS232 cable length according to Texas Instruments
Baud rate   Maximum cable length (ft)
19200        50
9600         500
4800         1000
2400         3000

https://www.lammertbies.nl/comm/info/rs-232-specs
You haven't mentioned baud rate requirements, but 500ft @ 9600 looks pretty good.
Also, RS232 drivers are push-pull whereas I2C is only pull down with a resistor pull up.  So it degrades faster with a cables capacitance, unless you lower the pull up resistance which increases power draw.
If you need faster baud rate, then you can look at RS-485 (differential) instead.  It pretty much the same from the CPU perspective, you just use a different driver chip.