So that sp3000 is a good light.
I use one in a 2.5x5 closet.
Gorilla tents are great but expensive imho, ya really dont habe to have a fancy tent, its one of the few things we van get away with buying cheap…
The sales rep is trying to well, “sale you”. Tell him kick rocks and watch the sp3000 review on cocoforcannibus.com. it works great in tents
90% of grow lights we all use are designed for greenhouses and infact, a grow tent is a greenhouse ffs 
Sorry I work in sales and distribution and I hate salesmen
Get you a used tent of Facebook Market or whatever cheap one you can find and use the sp3000 you got. spend that $ you saved on autopots, grow in coco-coir mixed with perlite at a ratio of 50-70% coco-coir to 30-50% perlite, use a simple cheap but trusted nutrient line like General Hydroponics or Jacks 321.
Careful when choosing nutrition lines as they will try to “sale you” also. .
Stay away from anything thats more then 3 parts. A 1 part nutrient like General Hydroponics Maxi-gro for veg and maxi-bloom fir flower does great.
Alot of nutrient lines have ridiculous amounts of bottles that are all over priced and they make you think you need them all, but you don’t 
Here’s my current grow if you want to follow along with it where i grow some nice smoke just about the most fool proof way possible 
Growing can be so simple it’s kinda boring actually till harvest of course