40 amp controller might be twice what you need.
Unless you have a special situation I think most get bored with the portable panels and they end up on the roof eventually.
Unless you are going big 24v panels it is not a huge deal to match components. A couple 100 to 160 watt panels and a 20 amp controller will serve you just fine.
https://www.solarblvd.com/products/two-solar-cynergy-100-watt-12-volt-solar-panels-with-y-connector/https://www.solarblvd.com/products/morningstar-sunsaver-ss20l-20a-12v-charge-controller/ > Members Solar Installations With Pics