The EA typically has fullsize cars and up. It's rare to only find up to a midsize there. Furthermore, National is typically very accommodating and if the aisle doesn't have a bag that will fit a modest amount of stuff (our assessment of your needs), then they will typically find something for you elsewhere on the lot.

You can definitely reserve a full-size from the get-go, but in our experience, it's not necessary since the aisle will usually have that and more.

Hope this helps. Safe travels!