If you're handy with electronics and have a soldering iron, I just solder together some 5W resistors in series and heatshrink them. A cheap anti condensation system for under $5 & very effective esp here in SW WA with our damp winters!
I've upgraded my SN 8" to a Moonlite and it's just a pleasure to use. I am now in the process of upgrading my 80mm refractor. The best part about the refractor series is that once you've committed and installed the Moonlite & decide to upgrade the scope later on (to another refractor), most Moonlite upgrades only require the flange to be changed (within limits of course as there are many 10's of OTAs out there)
As for EOS clip filters, unless you've got a modified camera, they're probably not going to do much.
Research on this site and guys like Brendan and Doug are far more qualified than myself (from my perspective anyway!) and have the results to prove it.
Finally, personally I would avoid an inverter as so much stuff these days can run off 12V - laptops to guiders to Canons, mounts, heaters, USB hubs etc etc. Basically what I've done is bought a Jaycar switching 240V/12V (variable) 15A which is more than enough if mains is available and I run my gear off a 30AHr battery and my load is under 5A (excluding laptop). Choose your battery based on your load & time you wish to run for and try and avoid inverters. I get about 4hrs on my system away from home and if I'm camping, I bring along my 40W solar panel (with MPPT) for charging the battery.
My 40W panel with the Silicon Chip MPPT kit (also from Jaycar) means I never need to use a mains supply to recharge my batteries. 40W is probably bare minimum btw. I build my own solar panels but even going down to Retravision etc (nearly everyone sells the blinkin things) I've found shops often have 1 or 2 orphan panels around 80 - 120W they want to get rid of for under $3/watt (thanks to our governments for cutting the rebate

). This is a very good price.
Good luck & let us know how you go.
Darrin...