Here you go: (XJ spring dimensions)
http://forums.off-road.com/jeep-short-w ... sions.html
I kept the leaves off my 99 XJ for just this reason when I put a Rusty's 3" spring pack on it... just in case... I'm still hunting for free wheel(s).
XJ springs are set up for spring over the axle (SOA), which yields more ground clearance than the Chevy Blazer (SUA) design... of course you can always change the center pin. The XJ is a very light vehicle (<3500 lb curb weight), so I would think stock XJ springs would do much better than Blazer springs.
You probably don't want the Rusty's springs... you can bet the spring rate will be too high for a small trailer.
Backspacing on stock XJ wheels is ~5" to 5.5" which is fairly deep for most trailer axles. If you're welding the spring perches on the axle yourself you can make this work... but you probably want to match the backspacing and tire size of your TV so you only need to carry one spare.