I also have the Renogy suitcase. One of the best additions I have bought. I can use it on the TT, TC, at home and my boat. And being able to aim it directly at the sun makes a huge difference. First I tried it just laying flat on the roof. Good hot sun high in the sky I thought it would do good. 1.5 amps. I tilted it slightly, about 6", to face directly into the sun. 5.5 amps!! If I can find room for it in an 8' camper then a 26' should be no problem. And you're not out a nickel as it stays with you. Those twin 6 volt batts have amazing storage. I would try them first without adding more. Especially if you might not keep this TT. JMHO