For what it is worth, most of the small TTs I've seen have come with and/or are equipped with a single 12 volt "marine deep cycle" battery with about 75-80 AH capacity. These batteries are slightly enhanced starting batteries, not true deep cycle batteries, and their main benefit is they are cheap, around $80 or so, which is why RV dealers provide them. Such a battery can at most provide you with 40 AH (or 480 watt-hours) of power without seriously degrading their useful life. A 100 watt solar panel will give you around 400 watt-hours per average day, enough for most. If you want to be really prepared even for a couple rainy days in a row, 200 watts of solar panels are plenty.
@Devocamper has a point about portable solar panels. The drawbacks to portable are two: (1) they require your attention to set up/take down, and (2) being portable, they are subject to theft. Permanent mounted panels and system have the drawback of being ineffective if shaded. It's a tradeoff. You pays your money and takes your choices.
I got carried away and built myself a 400 watt semi-portable solar system earlier this year (blame it on the COVID). 4-100 watt panels, two 125 AH AGMs, on a hand truck. The whole thing weighs a little over 200 lbs, but can power 1,600 watt-hours daily usage worth of stuff indefinitely. I added a 2200 watt (4400 watt surge) PSW inverter. The thing is capable of running my RV's AC, although not overnight.