Hi Philip,
TXCO is only needed for digital modes.
I use an Amazon Camera bag, with camera harness body strap and my two radios with a 6 AH Bienno LiPO battery. I added Power Pole adapters to the back power connectors, you can get those on eBay. Also a DC Y cable.
Please note that the 817 does draw power even when powered off, see :
http://www.ka7oei.com/ft817_pwr.html not much but if you don't use the radios for a while you may wind up with a dead battery. Happened to me once.
No need for SSB/CW filters, unless you plan on doing CW on the sats.
Do order a Mini-Circuits Low pass filter for the 2m side if you use an Arrow antenna otherwise you will get desense.Look for BLP-200+ (see past AMSAT-BB posts) Ignore the low wattage spec. This is needed for sats with 2M uplinks otherwise the third harmonic will ruin your UHF downlink. Been extensively covered on Twitter. Sat ops, including this one use it all the time.
73, Adrian AA5UK