Regardless or what you brew, you are going to probably need the ability to keep some reasonable fermentation temperatures.
If you are going for an "oktoberfest-like" beer, I would maybe suggest brewing an Alt...... it is a german style, malty beer that you could scale the hops back on just a bit and it would get you that "type" of beer. It is fermented with ale yeast which gives you a bit more flexibility on temperature. (German Ale Yeast is a good one for this)
Another option is to brew a "mocktoberfest"..... basically a festbier/oktoberfest grainbill, but use something like german ale yeast, or a kolsch ale yeast. Again - not a "true" oktoberfest, but will get you in the ballpark.
That said, these beers/yeasts are still going to benefit from cooler fermentation temps (lower 60's) and both beers are going to benefit from some conditioning at cooler temps after they are not done - but, a bit more forgiving and flexible than a lager.