Yes, you can report as a trade or business and pay self employment tax on your profit. But why do you want to pay more in taxes than you would treating the transaction as a short term capital gain ?
I'm curious as to why you would think that this is a good idea. Presumably you made a profit on this. Possibly you can deduct more of your expenses if they fall into the category of repairs rather than capital improvements, but you also subject your self to tax at the ordinary income rate rather than capital gains and to self employment tax (roughly an additional 12 % tax) Did you live in the house at all? If you buy a house and live in it for at least two years while you are fixing it up or after you fix it up you can likely exclude the entire gain. Even if you live in the house for less than two years you can still exclude gain but the amount you can exclude is lower. It his is a done deal then you should consult with a good tax attorney or CPA to determine the best way to report this on your tax return. If it is not a done deal, you might want to consult with a tax attorney on how to go about conducting this business. If you are willing to do this business in a certain way, most or all of the income can be sheltered from taxes saving you a lot of money and increasing the amount you realize from your labor.
Unless you are in the trade or business of buying and selling homes, you cannot treat as self-employed. This is an investment. But, your conclusion that you cannot deduct certain expenses as an investment are incorrect. See a good CPA and treat it correctly. You don't have the knowledge to do this on your own and attempting to do so will cost you more dollars then the fees you pay.
This answer is provided for general information only. You should seek advice from an attorney or tax professional.