Hi,
I agree that you really only need to replace the frequently used bulbs with LED's. Before finding low cost LED's, I was also thinking rather than spend $250 on bulbs, it was lower cost to spend $250 on solar and not worry about how much power the bulbs used.
For $250 you can buy 2 each 100 watt solar panels from this place.
SunElec.comFor $13 you can search for and find a 10 amp solar controller.
AliExpress.com Sure it takes 4 weeks to ship from China, but you will get it sometime.
You can also find 24 LED 5050 panels for about $1.20 each that will replace the conventional bulbs. What I did in my RV is take out the wires to the 1156 base, and connect them to the adapters included with the panels. Then plug 1 or 2 panels into each bulb location in my RV. Each panel used about 0.1 amps or 1.2 watts. For the porch light I used 4 panels, or 0.4 amps at 12 VDC, about 5 watts. It lights up the whole side of the RV and about 30' out.
Fred.