Pretty much any vehicle will work for chasing, but you just have to keep in mind it’s limits when you consider getting off the pavement.
The options are pretty much none for making the windshield hail proof. Even bulletproof windows crack when hit with hard objects. The closest thing for hail proof is the material they use on race cars, which I believe is a polycarbonate. The problems with that material are because it‘s relatively soft, it scratches easily and it’s illegal to use on a passenger vehicle. Even if you weren’t concerned about the illegal part, you would have to have tear offs on it like they do in NASCAR so you could continue to have decent visibility.
These are some of the reasons people generally go with hail guards for trying to protect their windows.
There are 5 main things to consider when selecting a chase vehicle: reliability, maintenance, comfort, driving cost, and are you willing to risk it taking some hail. Personally I would worry about reliability of any vehicle that is 19 years old regardless of brand. Even if it had all of it's major parts replaced - you still run the risk of something happening because no one designs vehicles to last that long (case in point - my chase partner's last vehicle had a plastic bushing that held the transmission shifter to the cable and it just got brittle and broke on a chase). Maintenance is important on even new vehicles (especially tires). You will be driving a lot if you chase so comfort is important. Another thing to consider is driving costs - you may like a certain big vehicle for comfort and off road ability - but can you afford to put gas in it? Finally there is an advantage to an older vehicle in that you might not be as fearful about hail. Even if you don't core punch and you try to avoid hail - sooner or later your luck will run out if you chase long enough (I have taken 3 inch hail and lost a windshield when in an area that wasn't even raining). If you have a brand new vehicle, your fear of hail might affect your chasing.
Bottom line - you can chase in any vehicle, but there are pro's and con's of your choice. I did see a guy chasing on a motorcycle once (which I wouldn't recommend for a lot of reasons).
I definitely second Randy’s concern about chasing in an older vehicle. I am a chase vacationer and always rent, but even with the relatively new cars you find at rental places, I am always paranoid that something is going to happen. In fact, one reason I prefer flying into large airports like Denver is for the large selection of rental cars. I have been given vehicles with bald tires, or with the “change oil” light on, so it’s good when there are enough vehicles available to get a proper replacement.
The point is, the reliability of your vehicle, driving the vast distances of the Plains, where you are often out in the middle of nowhere, possibly late at night, is analogous to having a seaworthy vessel in the middle of the ocean.
I also second Randy’s advice about tires… The problems I have had with rental cars mostly involved flat tires. Sure, roll over a nail on a dirt road and you’ll probably puncture even a brand new tire, but you need to stack the odds in your favor, and control what you can control, to give yourself the best likelihood of traveling without incident.
One of the worst things I could imagine is a vehicle that won’t start or move when you most need it to escape!