hi BW. this is my 2cents.
your mix does sound much like indoor. I guess many would disagree and it depends on type of soil but I wouldn't use that much peat ,if any and perlite in GG. peat offers nothing but water holding ability and with 33% of compost you have more than enough of organic metter for good dreinage and water holding ability (plus nutrients and beneficial microbes). I would consider water cristals. I would use perlite to loosen your soil if it's really hard clay or loam. again with high amounts of organic metter like compost you have already improved water holding ability for loose soils and soil texture/dreinage for clay soils. if the soil is light (sandy,rocky..) you don't need any perlite. good compost does both things when mixed with native soil. in poting mixes perlite offers dreinage for peat which has tendancy to get compact.
basicly I would make bigger holes (25gal is not a big hole imo) if you want bigger plants. and spend that peat (and perlite) money on good compost or worm castings even better. imo even 10-20% of compost is more than enough for any hole. oh and epsoma plant tone already includes micorizhae.
Thanks for the input man, the place I grow is a marsh like environment. I need good drainage for the soil. I'll definitely consider digging some bigger holes, i plan on having one or two 100gal holes, but the place is really shitty to dig holes, so we'll c how that goes! I think i should avoid water crystals due to the marsh place.
I also got some home made wormcastings that I plan on using, not much tho, maybe like 20 gals.
But i'll def think about that, thanks for the input man!