Hey Joe,
Sorry I've not responded. It's been a very busy day.

That does look a bit hacky! ;)

I noticed in your controller.

[HttpPost]
public ActionResult Submit(LocationModel someLocation)
{
    return View("~/Views/FindLocalThings.cshtml");
}

post you return a View("~/Views/FindLocalThings.cshtml"); have you tried returning CurrentUmbracoPage(); or RedirectToCurrentUmbracoPage(); instead?

I'm not sure if this is too far off your implementation but I recently built a contact form SurfaceController which may or may not solve your problem.

    using My.Website.Models;
    using My.Website.ViewModels;
    using System;
    using System.Linq;
    using System.Web.Mvc;
    using Umbraco.Web.Mvc;

    namespace My.Website.Controllers
    {
        public class ContactFormSurfaceController : SurfaceController
        {
            //This is the logic used when a request first hits the page
            [ChildActionOnly]
            public ActionResult Form()
            {
                return PartialView("ContactForm", new ContactFormViewModel());
            }

            //This is the logic used when return CurrentUmbracoPage() is called
            [ChildActionOnly]
            [HttpPost]
            public ActionResult Form(ContactFormViewModel model)
            {
                return PartialView("ContactForm", model);
            }

            [HttpPost]
            [ValidateAntiForgeryToken]
            public ActionResult Send(ContactFormViewModel model)
            {
                if (ModelState.IsValid)
                {
                    //Handle success with your own business logic

                    //Pass sent TempData to let the partial know it's been sent and hide the form
                    TempData["sent"] = true;

                    //Clear current form by redirecting to the current page
                    return RedirectToCurrentUmbracoPage();
                }

                //If it isn't valid return the current umbraco page with the current model
                return CurrentUmbracoPage();
            }
        }        
    }

And for the partial view:

@model My.Website.ViewModels.ContactFormViewModel
@{ 
    var sent = TempData["sent"];
    var isSent = sent != null && (sent as bool?) == true;
}

@if (isSent)
{
    <p class="title is-3">Message sent</p>
    <p>Thank you!</p>
}
else
{
    using (Html.BeginUmbracoForm<My.Website.Controllers.ContactFormSurfaceController>("Send", FormMethod.Post, new { @class = "form" }))
    {
        <fieldset>
            <legend class="title is-3">Get In Touch</legend>    

            <!-- a bunch of input fields which are bound using @Html.EditorFor(model => model.MyPropertyName) -->

            <div class="field">
                <p class="control">
                    <button class="button is-primary" type="submit">Contact Us!</button>
                </p>
            </div>
        </fieldset>
        @Html.AntiForgeryToken()
    }
}

And finally to include to the partial on the page simply use: @Html.Action("Form", "ContactFormSurface")

Admittedly I'm not using any Umbraco properties in my partial view, however I did use some Umbraco properties within the handle success part of the logic and that worked fine.

I hope this helped and it wasn't too far off tangent.

Thanks,
Jamie