Presumptive scheme u/s 44ae

26AS of an assessee states 620000 on which 1% TDS has been deducted u/s 194c, he has not made any investment during the previous year and will not do till 30th June for claiming deduction u/s80c.
Assessee is engaged in business of transport of goods.
if he Opt for 44ae than he will be having tax liability of around 31000 which he does not want to pay.
just because 26AS states 620000 he need to show his income atleast 620000.
questions :
1) whether he can show gross receipt u/s 44AD as definition of vehicle in Sec.44AE states only for "truck" ?
2) whether he can show receipt net of all related expenses
3) how can he save his tax liability ( except audit )