using a 5-1-1 fish emulsion should be fine every three or four weeks. i have never used the spikes before. since the spikes are low enough does not seem it will cause nutrient burn.
your choice but i would try one hill with spikes and one without. one hill i would use the spikes in combination with the fish emulsion and the other hill i would use straight fish emulsion.
start a third as an experiment and see what happens. my personal opinion. take it how you want.

1) send kids to catch 15 small bass.

2) beg wife to use blender

3) have a small party with beer and bbq

4) OUTSIDE let the boys grind the fish up in the blender until they are a nice puree.

5) Bet friend a 12 pack that you will take a sip of it and win by faking a sip. (great entertainment for adolescent boys)

6) store in used milk jugs.

7) add one cup to 5 gallons of water and pour directly on the pumpkin vines where they are coming out of the ground.

8) Enjoy GREAT pumpkins!

Here is a link that might be useful: My blog with cool pictures.