Eagle Cap runs a 10ga wire from the roof. If you plan on running 4 panels, you have 3 options:
If you get an MPPT Controller:
* Run them either all in series for a 80v circuit, the amperage down the wire will be no different than a single panel.
* Run them in two 2 pairs of 40v. The amperage down the wire will then be double, but still well within the limits of a 10ga wire.
* With an MPPT in either configuration, you could get a max of 33 amps charge @12v w/400 watts of panel.
PWM:
* All 4 in parallel. 4x the amperage, and the highest amount of loss due to cabling. The 10ga wire will handle it due to the average Impp is 5.5a, so ~22a.
* Major downside - the most charge you will get is 22a with the PWM. There is no voltage-to-amperage conversion with PWM, just the amps the panels put out directly.
I don't recommend a PWM for that many watts. You'll get a substantial amount of additional charge amps going with an MPPT.
Worth noting, I bought eight of these for my TC, and they're still on sale---
Grape Solar 100w Panel for $97 w-free shpgOn edit--
One other thought - sell that panel and controller you currently have and get 4 matching panels from Home Repot.
'15 F450, 30k Superhitch, 48" Supertruss, 19.5's, Torklift Fast Guns
'12 Eagle Cap 1160, 800watts solar, Tristar MPPT, Magnum Hybrid 3k Inverter
'15 Wells Cargo 24' Race Trailer, 600 watts Solar, TriStar MPPT, Xantrex 2kw inverter
'17 Can Am X3 XDS Turbo