Thanks to all for the advice.
Still lost the game, 64-56, but was able to play it close until the last minute. A 3 pointer with a minute left pulled me to within 2, but Hawaii scored the final 6 points to close it out.
I ended up doubling Doss and playing -4 with a slowdown. The only other change I made was to replace my PG, Collier (23 DEF), with Knight (46 DEF) in the starting lineup. Lost something slightly with BH/P but made up for it with DEF at the point (though Knight did foul out). Doss still scored 18, going 5-11 from beyond the arc. Shepherd, their other big scorer at C, scored 20. As suspected, playing -4 would create a lot of fouls inside and he went 10-12 from the free throw line.
I also suspected that Hawaii would play slowdown and double up on Sparks, and they did just that. Sparks was held to nine points, but my other scorer, Countryman, scored 16. It probably helped that I upped his distro (as well as Sparks').