Helpers do not appear to be available to take up more than 3"
http://www.summitracing.com/search/b.../?autoview=SKU
You may have to go to a tender spring which will not completely compress under static load and give you lower initial rate.
2.5" Tender Springs:
http://www.summitracing.com/search/B...c&autoview=SKU
Don't forget the Connector/Spacer:
http://www.summitracing.com/parts/EIB-SPACER250/
For this weekend, I guess, throw in the 3" helper and take whatever ride height that will give you with the perch set so they are slightly compressed.