poor mans cool cart would consist of an ice chest which you should already have, a $10 bilge pump and some hoses. the key is in the disconnects. water in, water out, circulating through some cool water. shouldnt be more than a $30 investment.
fittings from a radiator flush and fill kit can be incorporated and used along with hoses from a washing machine. parts you may have laying around. still need a pump.
if you want to go real cheap you can simply strategically place bags or blocks of ice on/over your heat exchangers. ice costs money so your paying for your cool down system anyway.
a gas powered blower can help as well, especially with your clutches.
too bad you arent closer. i have 2 setups in varying stages of assembly, but i just sold my last sets of disconnects.
if this is your first time at grass drags, simply use your head. shade and air movement will be alot of help. since there is probably no cash payback involved and your at the bottom of the learning curve, dont kill your sled. you will know if the sled is too hot. alot of cooling can be had using a blower.
then if you get the bug(and you will), invest in the needed equipment to gain a competative edge.