Vehicle hire and unsealed roads in Tasmania

I'm planning to come down again in August and spend about 3 weeks touring around. We intend to focus mainly on the NE and NW regions (eg Blue Tier, Tarkine) including doing a number of bushwalks (day trips only this time). Instead of using our own 4WD and coming over on the ferry, as we've done in the past for this type of trip, to avoid driving to Melbourne we plan to fly to Launceston and hire a vehicle.
From past experience many access roads into NPs, state forests and other reserves are unsealed and can be a bit rough/corrugated (eg Mersey Forest Rd). Of necessity we will be using roads like that at times and don't want to be restricted as to where we can go. Probably won't need a 4WD but AWD might be handy (Nissan X Trail or similar).
Does anyone have any recommendations or experiences (bad or good) with car rental companies in regard to allowing unsealed road driving (eg any disputes, unfair charges or ridiculous exclusions).
Is there a local company that specialises in hiring for this purpose (and may be more accommodating than the major operators)? I have already contacted one national rental company and they indicated that unsealed road usage is OK as long as they're mapped public roads. However their documented terms and conditions appear to read differently.
From past experience many access roads into NPs, state forests and other reserves are unsealed and can be a bit rough/corrugated (eg Mersey Forest Rd). Of necessity we will be using roads like that at times and don't want to be restricted as to where we can go. Probably won't need a 4WD but AWD might be handy (Nissan X Trail or similar).
Does anyone have any recommendations or experiences (bad or good) with car rental companies in regard to allowing unsealed road driving (eg any disputes, unfair charges or ridiculous exclusions).
Is there a local company that specialises in hiring for this purpose (and may be more accommodating than the major operators)? I have already contacted one national rental company and they indicated that unsealed road usage is OK as long as they're mapped public roads. However their documented terms and conditions appear to read differently.