Sounds like he's got it made.
One question, you meant 20x33x28 INCHES, not FEET, right?
Sounds like you're doing everything right and he's enjoying your company.
Ferrets appreciate the simplest things. They are very olfactory and love to sniff out new things they've never smelled before, like an empty pizza box, a take out box(empty) or someones dirty socks or shirt. They play forever with an empty shopping bag you brought the groceries home in and love things that smell and sound differently, but I'm sure you know that. I put ice cubes on a shallow tray for mine and watch them try to catch the cubes or I fill a 2" deep cake carrier lid with water and throw a few treats and toys into it and let them dive for it. There's tons of things for you to do with your ferret. Have you tried towel rides yet? Pull a beach towel along the floor in front of him until he hops on and then speed around the house until he either falls off(careful he don't hurt himself) or he climbs all the way up the towel to your hands. Get him some tubes to play with too, they love tubes like dryer vent tubes(make sure there's no wires poking out at the end anywhere).
You do not have to get a second ferret. Yes, a lot of ferrets like the company of others, but not all of them do. They have personalities, just like people. Some love ferret company, others will simply just tolerate it, others yet will never like it.
Ferrets were not socially animals originally, actually they were more or less solitary in the wild only seeking each others company at mating time. The whole social thing is something that came about since domestication(over 2000 yrs ago) and is a trait introduced by humans.
And since yours seems happy at this point, why ruin a good thing? Two ferrets will double your bills, which is especially important when looking at your vet bill.
There is one phenomenon though: you double the number of ferrets you seem to quadruple the amount of fun to be had by all. It's amazing.
Glad you're enjoying your weezil, keep up the good work.
Good luck to the both of ya.