Jefferson, we have two ~100 watt panels permanently mounted on our 233S. Previously they were installed on our Jayco hybrid. On both hybrids they were professionally installed, but I watched closely how they did it. I also removed the stuff from the Jayco.
Typically the wiring is run down the fridge vent by making a small access hole in the bug screen below the vent cover. On the 233S it was handy to install the controller in the unused plenum above the fridge, and run the two power wires to the main power control centre located below the fridge; careful about wiring with the cut-off switch.
I am not familiar enough with the IKSS to know if the fridge vent will work with the kitchen slide? Someone else with your specific model may know better.
For fastening to the roof, they just used four brackets per panel with one large screw per bracket. Dycor below the bracket and over the edges and screws to seal to the roof membrane. Some wire hold downs with small wood screws were used, but honestly I think the Dycor holds so well after it sets the brackets are probably not required. No issues after several years on the Jayco.
PS We are most often dry camping at dog shows, which usually means blistering heat in the direct sun in the middle of a fair ground or whatever. The dog show organizers tend to leave the shade for the pouches.
. I considered going the portable route when we got the Roo, but we carry soo much stuff in the trailer the panels would not fit easily.