My DH took up riding at age 43 when he met me. I knew his first horse long before I knew him.
Were I you, I might borrow or buy a western saddle for your current horse and put your DH on him in an arena with some standards or such around the space… so he can get a feel for direct reining and stopping and going. Riding figure 8s is hard work and lots of fun to learn without being scary. For my DH it was best for me to get him a set of laced reins so he could easily see/feel if his reins were even. He could NOT feel that they weren’t even, yours won’t either. We aren’t born knowing this stuff, even though you don’t remember NOT knowing it yourself. Honestly- I want all new riders riding ‘two handed’ so they can’t grab the horn and expect it to help. If he is neck reining, that other hand is going to hold the horn and pull him off balance.
Then go buy the 2nd horse you want.
For cheap, lightweight, comfy westerns, look at Fabtron.