Scratch the 5.4 off the list....not enough power.
The V10 is a monster and will get about 11-12 empty and 7-8.5 towing. Get the 4.30 gear or change the gears to a 4.30 if you can't find a good example.
I had a V10 Dually with 3.73 and I wished it had 4.30.
The 8,600 GVWR Suburban is an ideal tow machine with the 8.1 V8....the weak link is the pot metal receivers ...swap that out and you will not have any problems with the 8.1 Sub...MPG is similar to the V10.
Diesels are great...if you go diesel I would budget 1-2k for repairs to the 7.3 PSD for their common issues....
I would SPEND 3-5k on a 6.0 as soon as I bought it on upgraded BPD EGR cooler, coolant filter, new FORD MOTOCRAFT Oil Cooler...and I would put new head gaskets in when I replaced the head bolts with studs...I would also have the turbo cleaned / replaced.
I would only consider buying an 05 Excursion with the 6.0 PSD...the 03-04 has some unique issues. The thing about the 6.0's is that they have a fabulous 5 speed transmission.
One more thing on diesel excursions....diesel Excursions can have much less payload than a gasser.
The V10's are relatively trouble free with a few exceptions..
They have a COP (coil on plug) design...one ignition coil per spark plug...these can have intermittent failures...sometimes it's a simple fix to replace the cool boots...sometimes you have to replace the entire coil.
The exhaust manifolds can also break the exhaust manifold studs...it's a $600 plus repair.
Enjoy the Hunt.
Jeremiah