A 120 miles is a drive around the block so not much of a range! We would be looking at a range of at least 300 miles before even considering an EV for towing. No way would I be wanting 1 1/2 hours added to my journey of about 300 miles.
It is of course a matter of personal preference on how far you are prepared to tow before stopping, and to some extent it may also reflect past experiences through necessity. For example here in the UK most drivers would consider a 300mile leg a very long journey and with UK road conditions it can be quite stressful. But my relatives in Canada barely think twice about doing longer journeys in a day, and rather than referring to the linear distance they look at it in terms of time.
Granted present day models and the state of the charging availability would not meet your 300 mile range and recharge times, but that is using todays perception and not allowing for improvements that are coming in the not too distant future. Ok it won't change the speed at which old cars can charge, but where newer cars can recharge at over 100kW per hour then teh picture is not as bleak as you make out.
...Used models will potentially be affordable but will they be capable of towing?
Yes - but not necessarily as far as newer models.
Will used models be affordable and would you buy a used model with only 6 months or a years warranty? Cost of replacing a battery pack can be horrendous at present although they may come down in price by 2030. However more than likely in about 2028 we will trade in for another diesel that hopefully will last us another 10 years.
The very strong irrefutable evidence is that EV batteries are lasting far longer than you imply. Many EV manufacturers are offering multi year or very high mileage battery warranties, and the replacement rates on average are very low. There are some models where degradation is significantly worse than average, but equally many that are probably going to exceed the average by a considerable margin. It's not perfect (but then even ICE vehicle wear out eventually) but second hand EV ownership is are nowhere near as bleak as you continually try to make out.