You will never get the full wattage/amperage out of a solar system unless conditions are perfect which often they are not.
The samlex system you are considering is a bit pricey for its capacity.
May I suggest spending a little more money for a complete Renogy 400 watt system?
A much more capable system which gives you a lot of room for growth!
We have the one with the MPPT controller but a PWM will work ok too at additional savings.
With this setup all you need is 4 golf cart batteries, an inverter, battery selector switch, battery monitor, and you may never need to run the generator again! Solar systems are like pickup trucks. Buy a small one at first and you'll regret not going large later and then ending up spending more money when you realize you need more capacity.
Batteries are as cheap as 85 apiece form Sams Club but I recommend spending 112 apiece and get the premium (more lead, heavier plates) golf cart batteries instead-they will last longer.
BTW, what kind of batteries do you have? Most RVs come with dual purpose batteries which aren't good. If they have a cold crank amperage rating (CCA) on them, they are not true deep cycle batteries.
My system has my 2 group 27 batteries in addition to my 2 banks of golf cart batteries for a total of almost 600 amp-hours of battery capacity. The two 12 volt batteries are just for emergency use when the sun isn't doing enough to charge the batteries or if a 6v cell goes bad. I also may run all 3 battery banks if wife is using the hair dryer in the morning or if we are running the microwave longer than a minute or two. Not a good idea to run mixed battery capacities at the same time continually which we don't unless we are drawing a large load.
Don't forget, you should not go below 50% of the batteries capacity or you'll give the batteries in no time. Our Group 27 batteries would last a single season due to the fact that the heater runs all night where we camp in the summers-above 10,00 feet in elevation.