If you file an extension, you can wait until october to pay those taxes. you get dinged with interest during that time, but it's just like any other gamble on the stock market. if you think the stock will be significantly higher in sept/oct, may be worth paying interest on the taxes, too. as long as your money is working for you during that time.
i liquidated my 401k last year to buy BEHL, so i have taxes, interest, 401k penalties to deal with, but i way surpassed my break even last summer it and it's worked out so far. sometime between summer and fall this year, i'll sell enough to cover taxes and be riding virtually free shares after that.
not saying it's the best idea (some might call it the worst), but it is AN idea. and it's worked for me so far...
good luck to you either way.
and GO BEHL!