300W inverter will do, for TV and laptop charger. Morningstar Sure Sine 300 is costly, but it's silent and a good brand. If not this one, you'll still want "pure sine" inverter type. "Modified sine" inverters are dirt cheap, I bought one for purposes like yours for $25, but some 120V devices don't like it.
"One solar panel" may or may not suffice, depends on panel wattage. If you don't know its wattage because the nameplate is on the bottom side that you don't see, it could help if you at least told the size.
You need 200-300W total solar wattage (yes, despite having the alternator). Because 300W solar works like 60-80W during low overcast, and 10-15W when it rains.
When adding another panel, it has to be of the same or very close specs. If you have some small 50W panel, this is nothing, might need to remove it and install 2*100W.
Fridge runs on propane, but very often it draws 12V as well, and A LOT of it. Disconnect your battery and see if fridge even starts.
LED lights will save a lot of energy, install them if you haven't done so yet. Ops, Time2roll beat me to it.
Battery monitor is nice to have, you may always add it later.
