Another towing question

[ipso_facto]

I have an 80's 32' Excella rated at 8300 lbs dry according to the manual. Full, I expect it to weight at just under 10,000 lbs. I will need to tow this unit probably 2,000-3000 miles/year, not that much and not often. Most of it in the mountainous or semi-mountainous region.

I have a '90 F250 HD with 460, 4.10 rear, C-6 tranny and full size bed/super cab, the full towing package. It tows it nicely. Problem is, it doesn't like normal highway driving much and prefers 50-55MPH. At 65, the RPMs hit 3100 and mileage drops to something like 10MPG, empty. Towing, I got 8.5MPG at under 60, although I could get almost 10MPG if I kept the RPMs at 2500.

I need a vehicle which will be used as a daily driver 90-95% of the time and for towing this A/S the rest of the time. I want something that can get me 15-16 MPG at normal highway speeds and not get high RPMs - and still be able to tow without problems. I need an OD but I realize I won't be able to tow in OD.

My options are:

First, Get a smaller truck, with a small block V8, 351W or 350 Chevy. In either a "Heavy Duty" or non-Heavy Duty version. F250HD came with either big/small block motors and I suppose so did Chevy. Regarding the rear end, either 3.37 or 4.10. HD would come with a HD tranny as well.

Ford towing guide rates F250 HD with 351W and 4.10 rear at 8500 lbs as its towing capacity. So I would be exceeding it by 1500 lbs. How dangerous is that? Is that rating an absolute fact or merely a guideline? There was no 3.73 end available in "HD", only 4.10 and 3.55. With 3.55, it is rated at only 6500 lbs. I don't know the numbers for Chevy/Dodge but don't think they are really different.

I would like to hear from someone who tows a 32' unit with a small block V8 with any make. I realize I would want tranny cooler. I would like to know what kind of mileage it gets empty, towing, what RPMs it hits on the highway and what's the rear end. My main concern is, I don't want to overheat and ruin the engine or tranny, ending up penny wise but pound foolish. I don't care about towing performance, I just want to get from point A to point B safely without breaking anything.

Second, Get a Gear Vendor Overdrive. Pretty expensive option at about $3,000 and not sure how much MPG it would actually add. Probably none, because the only thing it does is it would lower RMPs by 22% as they claim. Meaning at 64, it will idle only 2200 or so, resulting in probably 12 MPG.

Third Re-gear the truck to 3.55 rear. According to Ford, I will lose 200 lbs of towing capacity. 460/3.55 are rated at 9,800 lbs of towing versus 10,000 with 4.10 rear. I hear this will lower RPMs by about 15%. So at 65, it will run at 2600 or so. Meaning at 65, get an extra 1 MPG and highway driving will be a better experience. Doesn't really save me any gas per se, just allows to drive faster.

It is very doubtful the 460 can get above 12MPG no matter what you do with it. So options 2-3 would only make highway driving more bearable, RPMs more normal.

I know I have other options too, like getting a diesel or keeping this truck and getting a small car for daily driving. I would get a diesel if I had to tow a lot, I doubt I want a diesel for only 2,000 miles/year. The small car option doesn't work for me either because it is an inconvenience.

Any comments would be greatly appreciated.