what CFM is your fan rated at? and your filter?
you want negative pressure, and having an intake fan makes it harder to get negative pressure.
it may not be financial viable at the moment, but your best bet would be to get a bigger filter and fan. its a good idea to get a bigger filter than you need, and a fan that is rated at just slightly lower cfm. that way you can't over power your filter, and on all but the hottest days, you have room to dial it back some, which makes it run quieter.
you want the fan to pull just slightly more air than its getting through your vents, that's "negative pressure". it keeps the smells in the tent and exiting through the filter, not leaking out into your house. an intake fan makes it harder to keep this happening.
your filter will work better at removing heat if you hang it near the ceiling. if its sitting on top of a bucket, its pulling cool air out of the bottom of the room, and leaving the heat at the top of the tent to build up during the day.