I had a similar experience with my 2005 Sightseer 29R. Every time I hooked up a trailer or my Toad, the fuse would blow for the tail lights and turn signals. Just adding 2 1157 bulbs were too much for the fuse! First, I changed all of my tail, brake and turn bulbs to LED. I bought the bulbs on Amazon in packs of 10. Current listing for 1157s is Everbrightt 10-Pack White S25 5050 1157 27SMD LED Replacement Bulb for RV Camper SUV MPV Car Turn Tail Signal Bulb $16.99. Current for 1156 EverBright 10-Pack White 1156 Led Bulb, BA15S 1141 1073 1095 1003 7506 LED Car Replacement RV Camper Interior Lights Turn Signal $16.99. Side marker and clearance 194 LED Light bulb, Yuekui 6th Generation, Non-Polarity,12V Lights for 168, 2825,T10 5-SMD LED Bulb White High Power Car Led Lights Bulb (Pack of 10) $7.99.
After talking with a friend about this issue, I also added a relay panel to the rear. All power for the trailer or Toad goes through the relay panel which has a hot wire to my house batteries. Now, the only power needed from the RV lighting systems is enough to activate the relay (flip the switch). No more blown fuses in my RV!
I don't know about your RV, my tail light fuses were under the hood on the driver's side. The flasher relays are under the driver's side dash. Just lift up on the instrument cluster. It is hinged toward the windshield and has Velcro to keep the vibration down.